Abstract: Ultra high performance liquid chromatography-high resolution mass spectrometry was applied to the inspection of phase Ⅰ metabolites of synthetic cannabinoid JWH-073 in human liver microsomes. Human liver microsomes were incubated in vitro with addition of JWH-073 to simulate its metabolic process in human body. 11 phase Ⅰ metabolites of JWH-073 were found in human liver microsomes, among which 6 metabolites were hydroxylized products. Hydroxylation was found to be the main pathway among the other pathways of carboxylation, dealkylation and carbonylation. Based on the mode of metabolism, metabolic sites, and intensities of response signals of metabolites, the hydroxylized metabolite (abbreviated as M4) was recommended as poisoning marker of JWH-073 in human urine. In practice, human urine sample should be collected, and main metabolites found in human urine sample should be screened and compared scrutinously in order to affirm the metabolic marker of JWH-073.