Mucocutaneous rashes are most often seen in syphilis and occur on the chest, abdomen, flanks and back of the trunk, but rarely on the face. Syphilitic pustules may occur in weak and malnourished patients, often with high fever and systemic symptoms. Diagnosis: The initial diagnosis is usually made by the patient’s physical signs, with rosacea, macules, papules, pustules, flat warts, and mucosal spots on the lips, oral mucosa, glans, and inner labia minora, and others such as alopecia, alopecia, and hypochromic or hyperchromic spots on the skin mucosa. The damage is characterized by polymorphic nature, with the exception of flat warts, which are widely symmetrical, slow to develop, without obvious itching and other conscious symptoms, and highly contagious, fading on their own without treatment and leaving no trace. However, the diagnosis can be confirmed by finding syphilis virus through laboratory tests. At the same time, the mucocutaneous rash should be diagnosed differently from pityriasis rosea, erythema multiforme, lichen planus, psoriasis, tinea corporis, etc. If the patient has a history of impure sexual intercourse, syphilis is more likely. The spiral of syphilis spiral is tightly regular, refractive, strong, active and easy to identify. The spiral of syphilis is very helpful for the diagnosis of stage I syphilis, especially when the chancre has appeared and the serum syphilis reaction has not turned positive.