The diagnosis of syphilis can only be made after a comprehensive analysis of the medical history, physical examination and laboratory tests. The laboratory tests for syphilis are: 1) Examination of syphilis spirochetes in tissues and body fluids (1) Dark-field microscopic examination: It is of great value for the diagnosis of early syphilis, including hard chancre, flat warts of second-stage syphilis and oral mucosal spots. If the result is negative, it is recommended to check for 3 consecutive days. (2) Immunofluorescence staining or direct fluorescent antibody test (DFA tests) (3) Silver staining: Showing the target spirochetes in internal organs and skin damage. 2.Serological test for syphilis (1)Non-syphilis spirochete antigen serological test 1)VDRL test: In addition to serological test, it is also used for cerebrospinal fluid examination to help the diagnosis of neurosyphilis. 2) USR test 3) RPR test: In addition to serum, plasma can also be used to do the test. (2) Syphilis spirochete antigen serologic test 1)FTA-ABS test: detects IgG antibodies to syphilis spirochetes, and is more sensitive than other syphilis serologic tests for stage I syphilis, and is positive 3 weeks after infection. 2) TPHA and TPPA 3) EIA (enzyme immunoassay): specificity of 99.5% when used for screening test, higher than RPR test; higher sensitivity than FTA-ABS test when examining patients with previous infection.