Abstract: OBJECTIVE To explore the feasibility of rapid identification of depressor substances in drugs. METHODS Method of azo test was applied to identify histamine and histamine like substances in drugs quickly, the result was compared with that of routine method indexed in Chinese Pharmacopeia. RESULTS Control substance of histamine showed positive reaction, the detectability of this method was 0.125 μg, it had good correlation between this new method and routine method. CONCLUSION It provides a new way to deal with the drug emergency induced by depressor substances.