The number of injections for a course of syphilis needs to be determined by the classification of syphilis. Syphilis can be divided into early syphilis, late syphilis, cardiovascular syphilis, neurosyphilis and so on. 1. Early syphilis (including stage I and II syphilis): the course of the disease is less than 2 years, you can choose benzylpenicillin, intramuscular injection in the buttocks, once a week, a total of 2-3 times. 2. Late syphilis (stage III skin, mucous membrane and bone syphilis): the disease duration is more than 2 years, benzylpenicillin can be chosen, intramuscular injection in the buttocks, once a week, a total of 3 times. 3. Cardiovascular syphilis: treat heart failure first when heart failure exists, and hospitalization should be done to avoid gihai reaction. Benzathine penicillin can be chosen, gluteal intramuscular injection, once a week, a total of 3 times. 4. Neurosyphilis: aqueous penicillin static drip for 10~14 days, followed by benzylpenicillin, gluteal intramuscular injection, once a week, a total of 3 times. There are other ways to treat syphilis, and the number of treatments will vary. It is recommended that patients with syphilis seek medical attention in a timely manner, and choose the appropriate treatment under the guidance of the doctor to avoid delaying their condition.