Abstract: OBJECTIVE To establish anin vitro model for screening drugs with inhibitory effects on monoamine oxidase (MAO)， and evaluate the effects of 26 Chinese medicine injections on MAO. METHODS 5-HT and benzylamine were used as the reaction substrates of MAO-A and MAO-B， respectively， and clorgiline and selegiline were used as positive controls， respectively. LC-MS detected 5-HT product 5-hydroxyindoleacetic acid (5-HIAA)， and GC-MS detected benzaldehyde product of benzylamine， which were used to evaluate the inhibitory effects on MAO. RESULTS In vitro experiments screened 24 kinds of Chinese medicine injections that had inhibitory effect on MAO-B， but had no significant inhibitory effect on MAO-A. CONCLUSION The components contained in the screened Chinese medicine injections are consistent with those reported in the literature. The method used in this study is feasible and can be used for large-scalein vitro screening of MAO-A and MAO-B inhibitory drugs， guiding the clinical rational use of such preparations.