The auricular hypoplasia generally refers to congenital microtia, which is caused by the hypoplasia of the first and second gill arches or the first gill sulcus during embryonic development, and may be accompanied by malformation of the eustachian tube, tympanic ventricle, or mastoid process caused by hypoplasia of the first pharyngeal sac. The majority of microtia are composed of small cartilage masses with no auricular shape and a more normal but displaced earlobe. There is no external auditory canal or tympanic chamber, and the auditory bones are hypoplastic, resulting in hearing impairment. Genetic factors are the main factor in bilateral auricular hypoplasia. Congenital and birth trauma are also etiological factors. The causative factors are swimming, showering, prolonged pus in the middle ear, and inappropriate medication dripped into the ear. As a result, prolonged moisture in the external ear canal, combined with a warm environment, allows for easy fungal growth. In addition, ear digging injury is also one of the important factors for secondary development of this disease. If the local skin is often scarred, the blood supply, elasticity and looseness are poor. It is not easy to form a wide and looser cavity that can accommodate the implanted stent tissue. Therefore, it is often difficult to clearly show the shape of the contour sculpted on the stent. What are the causes of bilateral auricular hypoplasia? Auricular perichondritis: Auricular perichondritis can be divided into two types: plasmacytic and purulent. The lesions are either serous exudate (plasmacytic) or pus formation (purulent) between the cartilage and the perichondrium. In the case of plasmacytosis, the auricle is often only swollen, elastic, not red, without obvious pain, and in some cases there is local swelling, burning and itching. Pseudocyst of auricle is an aseptic inflammatory reaction of the cartilage membrane. The etiology is unknown and may be related to repeated minor trauma such as pressure, touch and other mechanical stimuli. Septic chondromalacia is an acute purulent inflammation of the cartilage membrane and cartilage of the auricle, often due to trauma, surgery, frostbite, burns, and secondary infection of the auricular hematoma. It can cause cartilage necrosis leading to auricular deformity and should be treated seriously. Congenital microtia: Congenital microtia (Microtia), or congenital external middle ear malformation, manifests as severe auricular hypoplasia, atresia or stenosis of the external auditory canal, and malformation of the middle ear, while the inner ear is mostly normal in development and has some hearing through bone conduction. The clinical features of patients with congenital microtia involve mainly the auricle, external auditory canal and middle ear; the inner ear is often not involved. Treatment is required through total earwax reconstruction and auditory function reconstruction surgery. The treatment of congenital microtia consists of two main components, one is external auditory reconstruction and the other is auditory function reconstruction. In general, the outer ear canal is reconstructed first, and then the hearing function is reconstructed. The normal auricle is composed of thin skin and soft tissue wrapped with elastic cartilage scaffolding, and has an elastic thin shell structure, and is composed of the ear wheel, the opposite ear wheel, the ear screen, the opposite ear screen, the ear lobe, the ear nail, the triangular fossa, the navicular fossa, etc. The shape is convex and concave, so auricle reconstruction is a difficult and complex operation.