Mixed tumor of parotid gland, also known as pleomorphic adenoma, is a kind of parotid tumor containing parotid tissue, mucus and chondroid tissue, so it is called "mixed tumor". Mixed tumor of parotid gland is one of the most common tumors in oral and maxillofacial region. Originated from parotid epithelium. In addition to epithelial components, there are often mucus and cartilaginous tissues in tumors. Mixed tumor mainly occurs in parotid gland, followed by palatal gland and submandibular gland. Mixed tumors of parotid gland are more common in young people. Generally, there are no obvious symptoms, the growth is slow, and the course of disease can last for years or even decades.