There are many causes of external auditory canal deformity, including genetic factors, drug-induced malformations, mother’s infection during pregnancy and ear trauma. 1. Genetic factors: a major cause of malformation of the external auditory canal is genetic factors, genetic testing can be found in the mutant gene. 2. Drug teratology: mother taking ototoxic drugs during pregnancy, such as streptomycin, etc., can lead to abnormal fetal ear development, resulting in malformation of the external auditory canal, which may be accompanied by other ear symptoms. 3. Mother’s infection during pregnancy: mother’s infection of rubella, syphilis, etc. during pregnancy can also cause fetal ear development abnormality, which can occur in the external auditory canal malformation. 4. Trauma to the ear: If a trauma to the ear affects the external auditory canal, it can leave a malformation of the external auditory canal if it does not heal properly. The causes of external auditory canal deformity are complex, and are also related to factors such as infection of the external ear canal and exposure to radioactive substances. It is important to seek medical attention in a timely manner to identify the cause of the deformity and make appropriate treatment and therapy to minimize its impact on quality of life and hearing.