Syphilis is divided into stages I, II and III, and the rash has different characteristics in different periods. Syphilis is a sexually transmitted disease caused by syphilis spirochete infection. 1. Stage I syphilis: the main rash is a hard chancre, which often occurs on the external genitalia or anus, with a painless papule that quickly becomes necrotic, ulcerated, with clear borders, painless and itchy, and which can naturally subside after a period of time. 2. Second-stage syphilis: the main rash manifests as syphilis rash, which occurs everywhere in the body, and different syphilis rashes appear in different periods, maculopapular rash appears at the earliest time, which manifests as a rose-red or maroon round or oval rash, and fades away when pressed, and the number of lesions is relatively large, and they don’t merge with each other, and there is often no itchy symptom, and the next one develops into papulosquamous syphilis rash, which is round, slightly elevated, red to crimson, and is infiltrated by touch, and has no self-conscious symptom. The next development is a papular syphilis rash, which is round, slightly elevated, red to deep red, infiltrated to the touch, and mostly without conscious symptoms. Pustular syphilis rash is less common, for the inflammatory erythema on the base of the pustules, dry, crust or form a non-healing ulcer. 3. Stage III syphilis: the main rash manifested as syphilitic tumors, small pimples on the lower legs or internal organs, mucous membranes of the oral cavity and upper respiratory tract, and bones, which can seriously affect the patient’s speech and swallowing. If the diagnosis of syphilis, it is recommended to consult a hospital in a timely manner, under the guidance of the doctor for standardized treatment, so as not to delay the condition.