Oral and maxillofacial tumors are divided into two categories, benign and malignant, according to their biological characteristics and harm to human body. It is of great importance to identify benign and malignant tumors in clinical practice. Benign tumors can occur at any age and generally grow slowly, with the existence time ranging from several years to decades, and the weight can reach several kilograms, such as mixed tumors of parotid gland. Benign tumors tend to grow swollen, gradually increasing in size and squeezing out and compressing the surrounding tissues, with a spherical or lobulated appearance. The tumor has an envelope, no adhesion with surrounding tissues, and can generally move. Patients usually have no conscious symptoms, but pain may occur when pressing adjacent nerves, secondary infection or malignant transformation. Lymphatic metastasis does not occur. Generally, it has no effect on the body, but if the tumor grows in some important parts, such as the root of tongue and soft palate, it may also have difficulty in breathing and swallowing and endanger the life. Pathological examination can reveal that the cells of benign tumors are well differentiated and the cell morphology and structure are similar to normal tissues. Common benign oral and maxillofacial tumors include: fibroma, lipoma, enamel-forming cell tumor, neurofibroma, hemangioma, etc. The characteristics of malignant tumors are very different from those of benign tumors. Generally, they grow faster and are infiltrative. Carcinoma mostly occurs in the elderly, and sarcoma is mostly seen in young adults. Malignant tumors can invade and destroy the surrounding tissues, so the masses are ill-defined and restricted in activities. When malignant tumor grows infiltratively to the surrounding area, it can destroy the adjacent tissues and organs and cause dysfunction. For example, damage to facial nerve can cause facial palsy; invasion of sensory nerve can cause pain or numbness; when involving jaw bone, it can cause loose teeth and pathological fracture; when invading pterygopalatine recess, occlusal muscle and internal pterygoid muscle, it can cause difficulty in opening. With the growth of tumor, cancer cells may gradually invade into the nearby lymphatic vessels and blood vessels to metastasize. Toxic substances produced by the rapid growth and destruction of tumor may cause “cachexia” in the advanced stage of tumor. Patients often die due to rapid growth, metastasis, invasion of important organs and cachexia. Pathological examination can reveal that the cells of malignant tumors are poorly differentiated, with heterogeneous cell morphology and structure, and abnormal nuclear division. Common oral and maxillofacial malignant tumors include: oral squamous carcinoma, fibrosarcoma, malignant lymphoma, malignant melanoma, mixed tumor malignancy, etc.