Tonsillectomy is one of the most common surgical procedures of head and neck surgery. Comparing with the common complications of tonsillectomy include hemorrhage, pain, infection and laryngeal trauma. Subcutaneous emphysema and pneumomediastinum are relatively rare. We report the case of a 32-year-old man suffering from recurrent tonsillitis was admitted for tonsillectomy. Subcutaneous emphysema and pneumomediastinum developed after the date of tonsillectomy under general anaesthesia and with endotracheal intubation. His condition got improved gradually with conservative treatment. He has been regularly followed up for half of a year after discharge and showed good recovery. This article describes our experience with clinical symptoms, diagnosis, treatment and prognosis of this case, suggesting that it is very important to separate the tonsil from its fossa for avoiding complications.