Abstract: 0.20 mL of the sample of blood or urine was taken and shaked vortically for 1 min with 0.60 mL of acetonitrile, and then centrifuged for 10 min. A portion (0.40 mL) of the supernatant was taken and diluted with 1.1 mL of 10 mol·L^-1 CH₃COONH₄ solution (pH 7.0); after shaking for 1 min, the solution was filtered through 0.22 μm filtering membrane and the filtrate was passed through the HLB online solid phase extraction column for enriching and purifying the 31 analytes (i.e., the constituents of poisonous plants) by elution with mobile phases of (A) water, (B) methanol and (C) acetonitrile. The eluates obtained were then separated by gradient elution using Poroshell 120 EC-C₁₈ column as stationary phase and (A) 10 mol·L^-1 CH₃COONH₄ solution, (B) acetonitrile as mobile phases, both of which contained 0.1% (φ) of formic acid. The 31 analytes in the eluates were then determined by tandem MS. Linear relationships were obtained between values of peak areas of the 31 analytes and their mass concentrations in definite ranges, with detection limits (3S/N) in the range of 0.01-5.00 μg·L^-1. Test for recovery was made by standard addition on the base of blood sample or urine sample as matrixes separately, giving results of recovery of the 31 compounds in the range of 90.4%-107% for blood sample and of 90.0%-103% for urine sample. Values of RSDs (n=6) ranged from 0.2% to 2.6% and from 0.3% to 2.9% for the 2 kinds of samples respectively.