Abstract: UHPLC-MS was applied to the determination of 5 poisonous peptides, i.e. α-amatoxins, β-amatoxins, γ-amatoxins, dihydroxy-phallotoxins and carboxyl dihydroxy-phallotoxins in mushrooms. The homogenized sample was extracted ultrasonically for 15 min with methanol. After centrifugation, the supernatant was evaporated to dryness by N₂-blowing in a water bath at 50℃ and then the residual was dissolved and made up to 3 mL with methanol (1+9) solution. After filtering on 0.2 μm filtering membrane, the filtrate was purified with solid phase extraction column. Acquity UPLC HSS T3 chromatographic column was used as stationary phase, and the mixture of 0.1% (φ) formic acid solution (containing 5 mmol·L^-1 ammonium acetate) and methanol mixed in different ratios was used as mobile phase in gradient elution. ESI⁺ and multi-reactions monitor mode were adopted in MS/MS. Linear relationships between values of peak area and mass concentration of the 5 poisonous peptides were kept in the same range of 0.05-1.00 mg·L^-1, with detection limits (3S/N) in the range of 0.100-0.300 mg·kg^-1. Values of recovery found by standard addition method were in the range of 54.9%-106%, and values of RSDs (n=6) were less than 7.5%.