Malignant tumors of parotid gland develop rapidly compared with benign tumors, and usually invade the surrounding normal glands or adjacent nerves within a short period of time, and also invade in the direction of the lateral skin, causing abnormal skin changes. The clinical manifestations of different types of parotid malignant tumors are as follows: 1. High degree of malignancy: such as adenoid cystic carcinoma, which invades the nerve earlier and has the characteristic of neurophilic growth, and can cause facial nerve dysfunction at the early stage. Invasion of zygomatic branch causes abnormal eye closure, invasion of buccal branch causes shallow lip-facial groove, invasion of mandibular margin branch causes skewed lips, etc.; 2. Low malignancy: slow growth, such as highly differentiated carcinoma and mucinous epidermal carcinoma, with growth characteristics similar to benign tumors. It has no infiltration to normal tissues of parotid gland in early stage and has no effect on adjacent facial nerve dysfunction.