Abstract: UPLC-MS/MS was applied to the determination of the residues of 4-hexylresorcinol in fresh Coprinus Comatu. The sample was ultrasonically extracted with acetonitrile, and the extract solution was purified with SPE-C18 column. The purified solution was separated on an ACQUITY UPLC BEH C18 column, with a mixture of acetonitrile and 0.1% (φ) formic acid solution as mobile phase for gradient elution. EI and MRM were adopted in MS. Linear relationship was found between peak areas and the mass concentration of 4-hexylresorcinol in the range of 5.0-500.0 mg·L-1, with detection limit (10S/N) of 1.0 μg·kg-1. Recovery rates obtained by standard addition method were in the range of 86.7%-94.4%, and RSDs (n=6) were less than 2.2%.