The severity of latent syphilis is usually related to the presence or absence of treatment and cannot be generalized. Latent syphilis is a condition in which there are no clinical symptoms, but the syphilis seropositivity is positive. It is usually more contagious within 2 years of infection when untreated or incompletely treated, and relatively less contagious after 2 years. Latent syphilis is prone to invade the patient’s lymph, blood vessels, nerves, bones, etc. If the patient does not actively carry out the treatment, it may progress to overt syphilis, and if standardized and thorough treatment has been carried out, regular review is sufficient. Therefore, the severity of latent syphilis is related to whether or not it has been actively treated. It is recommended that patients with latent syphilis actively cooperate with their doctors to carry out standardized treatment and regular review. Sexual intercourse should be avoided before the end of treatment to prevent transmission to others.