According to statistics, about 800,000 of the hearing and speech impaired patients in China are children under the age of 7. Although hearing aids can enable some patients to obtain or improve their hearing, they are ineffective or inefficient for many patients with severe and profound bilateral deafness. By severe and profoundly deaf patients, we mean people who have no functional hearing and have had poor or ineffective results with high-powered hearing aids, and whose only hope now is to receive a cochlear implant. Cochlear implantation is a technology that implants an artificially manufactured electronic hearing device into the cochlea of patients with severe or profound sensorineural deafness, stimulating the patient’s remaining auditory receptors, transmitting information to the auditory center, producing hearing, and thereby restoring speech communication and returning the patient to the audible world. With hearing, people can communicate with each other and civilization can spread. The scientific study of hearing reconstruction dates back three hundred years, and in 1790, Volta was able to experience the sound of boiling liquid in the head by inserting a metal rod in each ear. In the 20th century, with the advent and development of high-tech technologies such as microelectronics and computers, artificial hearing technology developed at a rapid pace. From the first attempt at cochlear implantation in 1970, more than 300,000 people have undergone cochlear implantation surgery and restarted their lives as normal people. China has also had more than 30,000 polycone cochlear implants through 2013. As a biomedically engineered device, a cochlear implant converts acoustic signals into electrical signals that directly stimulate the auditory nerve fibers in the cochlea, thereby producing the sense of hearing. At present, the main representative cochlear implants in the world are Med-EL from Austria, Cochlear from Australia and Advanced Bionics from the United States. China’s own cochlear implants include Norcon, Lixinte and other brands. These cochlear implant systems are composed of two parts: in vivo and in vitro. The in vivo device consists of electrodes and a receiver/stimulator, while the ex vivo device consists of a speech processor, a directional microphone and a transmission lead. The cochlear implant has given hope to deaf patients, especially to children with prelingual deafness, and has revolutionized the future of deaf children, a high tech technology that has gained international recognition in the medical community. However, in the face of complex conditions, difficult surgical operations and expensive medical costs, doctors must choose carefully in order to achieve good post-operative results for patients with cochlear implants. In general, cochlear implantation is an option for patients with severe or profound deafness in both ears, who cannot benefit from high-powered hearing aids, and whose lesions are diagnosed in the cochlea, if there are no contraindications to surgery. Although cochlear implants offer new hope for patients with severe and profound deafness, they do not mean that all patients can be implanted, and it is important to have a proper understanding of cochlear implants and appropriate expectations. It is important to understand both the joy of life that cochlear implants have brought to many deaf people and their limitations: First, cochlear implants cannot repair a damaged hearing system. If only a few auditory nerve fibers remain, they will not be able to transmit enough information to the brain. Understanding a complex sound like speech requires more auditory nerve fibers than just perceiving the sound, so the difference between the effects of a cochlear implant and a cochlear implant is the difference in the number of healthy auditory nerve fibers left in the patient. Unfortunately, damaged auditory nerve fibers cannot be repaired or replaced medically at this time. Secondly, although cochlear implants are helpful for deaf people, they are not perfect, and they are far from being able to achieve normal hearing capacity, which should be fully understood. Therefore, when a deaf patient considers a cochlear implant, he or she must first determine if he or she is a qualified candidate for a cochlear implant. And when we decide to have a cochlear implant, it is important to first get a professional opinion so that you can fully understand the results you can expect to achieve. There are conditions and criteria for patient selection for cochlear implants, namely indications for cochlear implants. Not all patients who are profoundly deaf or whose hearing aids have not worked are suitable for cochlear implants. Factors that affect the outcome of the implant include the duration of deafness, the age at which the deafness occurred, the cause of the deafness, the condition of the nerve fibers in the inner ear, the imaging of the inner ear, and so on. In addition, the patient’s desire to regain hearing and the family’s financial support may also affect the outcome of the cochlear implant. The selection criteria for cochlear implants are the same for adults and different for children. The same criteria are: hearing with severe or profound sensorineural deafness, hearing loss that cannot be improved by hearing aids or other devices, a strong desire to improve hearing and good psychological quality, support from family and friends, proper understanding of cochlear implants and appropriate expectations, no contraindications to surgery, and other criteria such as accessibility to the cochlear implant center and financial resources. Other criteria such as accessibility to the cochlear implant center and financial means. The different selection criteria are: adults must be postlingually deaf (with some language base), but there is no clear age limit, and young adults, middle-aged adults, and older adults can be implanted as long as they are postlingually deaf and meet the requirements for surgical anesthesia. In pediatric patients, the procedure can be performed at the youngest age of 12 months, and in some special cases, the age of implantation can be several months earlier. Patients with prelingual deafness can have good results before the age of 8 years, especially before the age of 4 years. If the patient is fitted with a hearing aid for 3-6 months prior to surgery and undergoes aural rehabilitation, this will greatly help to improve post-operative speech and language skills. It is important to develop a complete educational program for hearing rehabilitation for pediatric patients, with adequate financial and material resources for parents. In addition to this, children should be excluded from conditions that make them unsuitable for surgery, such as bilateral incomplete or absent auditory nerves, nerve damage causing auditory nerve block, significantly low intelligence, and a risk rate of implantation that exceeds the benefit. There are also factors that influence patient selection, such as patients with degenerative neurological disease and cerebrovascular pathology are not suitable for cochlear implantation. There are also certain risks associated with cochlear implant surgery, such as facial palsy. In conclusion, cochlear implants have patient requirements and selection criteria, and it should not be assumed that any patient who is profoundly deaf or who is ineffective with hearing aids can have a cochlear implant. To date, it is not possible to predict with any degree of accuracy what the outcome of a cochlear implant will be. For some people, it is a long, slow process, while for others, it can take only a few weeks to achieve good results, such as patients who lose their hearing suddenly due to a pathology and have a cochlear implant in a very short period of time. The in-the-ear portion of the cochlear implant is surgically inserted into the head between the muscle behind the ear and the skull. Prior to surgery, the surgeon conducts a thorough audiological, medical and psychological evaluation of the patient and gives the necessary preoperative hearing rehabilitation training. The audiological evaluation focuses on the nature, extent and cause of the patient’s deafness and includes both subjective and objective audiological examinations. The medical evaluation includes otologic and general examination, CT and MRI of the middle ear, inner ear, and auditory nerve, and assessment of the patient’s suitability for general anesthesia and the presence of other factors limiting surgery. The preoperative preparation includes preoperative fitting of hearing aids and the necessary aural rehabilitation to enable the patient to respond correctly to sound, which will be of great help in postoperative adjustment and rehabilitation. The surgery usually takes about 2 hours. The wound healing time after surgery takes about 7 days. One month after the surgery, the patient returns to the hospital to be fitted and adjusted to the external equipment. Specialists and audiologists turn on the computer program in the speech processor and adjust the program in the speech processor to the patient’s level of comfort with the sound, so that the patient can hear more comfortably and better. The patient feels a completely new signal after the cochlear implant, and although this allows him to feel more and more comprehensive signals, it is not exactly the same as the original signal, and he must relearn and understand these new signals. Since the patient needs a period of adaptation to the sounds he hears after the implantation, he needs to come to the hospital periodically to have the speech processor tuned. At the same time, the patient has to undergo hearing and speech rehabilitation. For post-speech deaf patients, training usually takes a few months, while for pre-speech deaf patients, it takes 2-3 years to achieve the desired results. In conclusion, there are many factors that affect the outcome of a cochlear implant: the duration of deafness, the age at which it occurs, the age and deafness-causing factors at the time of surgical implantation, the condition of the auditory nerve fibers in the inner ear, the degree of desire to rebuild hearing and rehabilitation training, the presence of deformities in the inner ear, and the skill level of the surgeon. But regardless, cochlear implants offer hope and options to regain hearing for deaf patients for whom medical and hearing aid interventions have failed or are ineffective. Currently, approximately 300,000+ people worldwide have adopted different types of cochlear implants, and about half of them are children. Cochlear implants can help people with severe or profound deafness to communicate better through hearing, thereby enabling them to have more educational and employment opportunities and to return to mainstream society.