One side of tonsil is enlarged by 3 degrees, it may be congenital enlargement, if there is no symptom, it can not be treated, if there is symptom that affects breathing and swallowing, it can be surgically excised; it may also be caused by tonsillitis and tonsil cancer, it can be surgically treated and treated with medication. 1. Tonsillitis: when patients have the symptom of 3 degrees enlargement of one side of tonsil, it may be caused by tonsillitis. Patients can follow the doctor’s advice to take surgical treatment, surgery is generally in the acute inflammation subsides 2-3 weeks after the main tonsillectomy surgery. After the operation, patients need to follow the doctor’s instruction to apply amoxicillin clavulanate potassium, cefuroxime and other antibiotics for anti-infection treatment. 2. Tonsillar cancer: for tonsil cancer caused by tonsil enlargement of 3 degrees on one side of the tonsil, patients can take surgical treatment according to doctor’s instruction, mainly adopting the surgical methods of transoral surgery, open surgery and reconstruction surgery. According to the specific condition, radiotherapy can also be carried out. If the patient has 3 degrees enlargement of one side of tonsil, he/she should consult doctor in time to find out the cause and follow the doctor’s instruction for treatment.