A negative syphilis test for one month does not completely rule out syphilis. Because the human body may carry syphilis spirochetes after infection with syphilis spirochetes in a low reproduction state, and at this time to do serological tests, it is often negative, which is often clinically referred to as the incubation period of syphilis. When a patient is infected with the syphilis spirochete, the replication level of the spirochete is so low that it may be difficult to detect its presence in serological tests. The duration of the incubation period of syphilis is related to the patient’s own constitution and the number of infected spirochetes. If the patient is infected with syphilis and has a very poor constitution, it is possible that the symptoms of syphilis may be manifested in a very short period of time. However, if the number of infected syphilis spirochetes is relatively small and the patient is very strong, it may take 3-4 months to show the symptoms of syphilis. Therefore, syphilis cannot be completely ruled out for one month. Clinically, it is recommended that syphilis serology tests be done 1 month, 3 months and 6 months after the suspected syphilis patient has had sex, and if all are negative, syphilis can be ruled out.