Abstract: A method for determination of triptolide and wilforlide A in animal liver by LC-MS was proposed. The animal liver tissue sample was extracted with acetonitrile, and the extract obtained was purified by gel permeation chromatography (GPC) to eliminate the interference of matrix. Eluate from the GPC column was evaporated to near dryness by N2-blowing at 40 ℃, and the residue was taken up with 0.5 mL of methanol, which was used for LC-MS determination. Linearity ranges of triptolide and wilforlide A were kept same between 5-1 000 μg·L-1, with same detection limits (3S/N) of 1.0 μg·L-1. Recovery and precision were tested by standard addition method and the results obtained were as follow: values of recovery in the ranges of 69.3%-77.8% for triptolide and 73.1%-77.2% for wilforlide A; values of RSD′s (n=5) in the ranges of 3.2%-3.3% for triptolide and 2.3%-3.0% for wilforlide A respectively.