Abstract: In order to retrospective analysis of biomedical samples exposed to nerve agents sarin (GB) and soman (GD), a method for determination of GB tyrosine adducts and GD tyrosine adducts in exposed animal plasma as a biomarker was developed by liquid chromatography/quadrupole-time of flight mass spectrometry(LC/Q-TOF MS). After optimizing different sample preparation processes and a series of instrumental parameters, the adducts were analyzed by LC/Q-TOF MS in positive electrospray ionization mode. After centrifugation, 50 μL plasma was added into 50 μL 10 g/L Pronase E in ammonium bicarbonate（50 mmol/L）and incubating at 37 ℃ for 2.5 h. The supernatant was analyzed after filtered through 0.5 mL molecular mass cutoff filters (10 ku) under centrifugation at 16 000 r/min for 15 min. The method is rapid, simple and reliable, which is suitable for analyzing the phosphylated tyrosine adducts in blood samples from the rabbits injected with LD₅₀ of GB.