With the development of modern science and technology, especially with the introduction of optical fibers in the 1960s, neuroendoscopy and its accessories have been continuously improved, and the development of endoscopic tubes with finer diameters and lighter weight, together with ideal microsurgical instruments, ultrasound guidance, CT and MRI three-dimensional reconstruction images, ultrasound suction, and lasers, have made neuroendoscopy an important technological field of neurosurgery, which has provoked more interest and concern of neurosurgical colleagues. Currently, intracranial tumors can be biopsied, resected, or intubated for radiotherapy or/and chemotherapy after being localized by CT and MRI three-dimensional reconstruction imaging with ultrasound and stereotactic techniques for neuroendoscopic surgery. Previously, conventional stereotactic biopsy of deep cerebral tumors with unknown diagnosis is blind and dangerous, while endoscopic stereotactic biopsy can select the non-vascularized area for sampling, and selective sampling of multiple sites under direct vision can ensure sufficient volume of sampling, thus improving the positive rate of biopsy. In case of bleeding, hemostasis can be performed under direct vision. The biopsy can clarify the nature of the lesion and allow for the selection of relevant treatment options. Parenchymal tumors can be localized with the aid of a stereotactic device after calculating target coordinates on CT or MRI, or by ultrasound guidance. After successful localization, the endoscope is inserted and secured, and the operator performs the operation under direct endoscopic vision or under television screen monitoring. For cystic tumors, the strategy is to first remove the contents to relieve the cranial hypertension, and then use microscopic instruments or lasers to remove the tumor nodules or part of the capsule wall through the endoscopic operation channel. If the tumor nodules can not be completely removed, the tumor nodules can be cauterized with lasers or high-frequency currents, which basically can be completely removed or most of the tumors can be removed, and the malignant tumors will be treated by a catheter or a drug storage capsule built into the capsule in order to facilitate the post-operative radiotherapy and chemotherapy. For substantial tumors, the lack of space within the brain parenchyma for endoscopic operation makes the illuminated fiber optic mirror blurry, resulting in unclear operative field and difficult operation. Especially for deep brain tumors, in the past, only endoscopic biopsy can be carried out after placing the rear-loaded radiotherapy, and occasionally with the help of laser vaporization of small tumors; nowadays, because of the development of the endoscope for resection of deep brain tumors and the application of the “double trocar method”, it has been possible to carry out total resection of tumors with diameters of less than 3cm in the deep part of the brain, if the tumor is more than 3cm, the tumor can be endoscopically resected first. If the tumor is more than 3cm, endoscopic resection can be performed to remove part of the tumor first, and the post-installation catheter can be placed to perform intratumor radiotherapy with better therapeutic effect. It has been proved that endoscopic resection of brain tumors has the following advantages: the best surgical access can be selected, avoiding the functional area and important structures such as neurovascular, and the tumor site can be reached directly without cutting a large part of the cerebral cortex and pulling the normal brain tissue with force. Therefore, endoscopic resection of small and medium-sized brain tumors is a safe and effective treatment method with precise and light injury and low mortality rate. Intracerebroventricular tumor is a better indication for endoscopic treatment. The intrinsic cavity of the ventricle can better display the ventricular tumor and its surrounding structures, and the operation of the ventricular system can also be monitored through the TV screen to control the direction and depth of the endoscope. The principles of endoscopic surgery for intracerebroventricular tumors are to take biopsy to clarify the nature of the tumor, to resect the tumor, to open the cerebrospinal fluid circulation and to reduce the intracranial pressure. For tumors within the third ventricle, the third ventricle can be accessed through the enlarged interventricular foramen for operation to remove the tumor, and ventricular collapse must be avoided during endoscopic surgery for intracerebral tumors. It is believed that the use of endoscopic technique to remove part of the cystic wall to open the cystic cavity to the ventricle for third ventricular colloid cysts can avoid the risk of injury to the fornix, doudoune montante vein, septal vein, and choroid plexus caused by separating the interventricular foramen, and also can receive good therapeutic effect. Neuroendoscopy can also assist conventional surgical treatment. Endoscopic surveillance through the unilateral nasal pterygoid sinus approach for pituitary adenoma resection has the advantages of good illumination, clear field of vision, multi-angle observation and identification of local anatomy, increasing the accuracy of surgery.