TRUST (Toluidine Red Unheated Serum Test) is a negative serologic test that is within the normal range, but cannot exclude syphilis. TRUST mainly detects anticardiolipin antibodies in serum, which belongs to a kind of non-syphilis spirochete antigen serologic test, and its sensitivity and specificity are poorer than that of syphilis spirochete antigen serologic test, and it has a certain probability of false-negative, so TRUST negativity can be seen in normal people, and also can be seen in some patients with syphilis. It can be negative during the window period of syphilis, or it can be negative in the anterior banding phenomenon when the titer is high, and it can be detected positively when the serum is diluted. A positive TRUST serologic test has a reddish flocculent and can be used routinely or to screen large populations. The diagnosis of syphilis needs to be combined with its epidemiological history, clinical manifestations and laboratory tests, and it is recommended to consult a specialist rather than make the diagnosis on your own.