Symptoms of oral syphilis infection are generally categorized into three phases, which are manifested by the symptoms of chancre, mucous membrane plaques, and trephines in the mouth and lips. 1. Chancre of the lips and mouth: The chancre of the lips and mouth mainly manifests as the symptoms of stage I. The infection site will have yellowish red or dark red ulcers covered with brownish red spots. A yellowish-red or dark-red ulcer appears at the site of infection and is covered with a thin brownish-yellow crust, which is usually painless. However, there is a brittle bone-like sensation when the base of the ulcer is touched, and there are also swollen lymph nodes. 2. Mucous membrane spots: the mucous membrane damage of stage 2 syphilis can occur in the gums, tongue, lips and other parts of the mouth. Grayish-white shiny and raised plaques appear on the surface of the infected area, and their shapes are usually round, oval, or ring-shaped, and they are prone to erosion. 3. Treponema: it is the typical damage of stage III syphilis. The infected area shows elastic lump with fluctuating feeling, and it will be ulcerated after deterioration. The treponema in the palate can destroy the bone, which is easy to cause tissue perforation. Syphilitic tumors on the tongue are lobulated and complicated by white keratosis or leukoplakia on the dorsum of the tongue at the edges of the atrophy. When the patient suspects that the oral cavity is infected with syphilis, he should go to the regular hospital in time, and be treated under the guidance of professional doctors.