Polymorphic adenoma, also known as mixed tumor, is the most common type of salivary gland tumor and is found in the parotid gland. This tumor can be divided into two types depending on its composition: 1. cell-rich type; 2. mesenchymal-rich type. It is generally believed that the former is prone to malignant transformation and the latter is prone to recurrence. Polymorphic adenomas are slow growing, often without conscious symptoms, and have a long history. The mixed tumors of parotid gland are mostly located in front of the ear, with clear boundaries, medium texture and nodular shape on palpation, and generally movable. When the tumor grows slowly for a period of time and then suddenly appears accelerated growth with symptoms such as pain and facial palsy, malignant change should be considered. For the treatment of mixed tumor, it should be surgically removed, and the tumor should not be simply removed, but must be removed together with the surrounding parotid gland in order to achieve the purpose of radical cure. Regular post-operative follow-up should be performed to detect any problems in time.