A gas chromatography-triple quadrupole mass spectrometric(GC-MS/MS) method was established for the determination of alkyl phosphoric acids，metabolites of organophosphorus nerve agents in urine.The samples exposed to organophosphorus nerve agents were detected by MS/MS using chemical ion source(CI ) in negative ion mode under selected reaction monitoring(SRM) mode.Both quantification and confirmation ions were optimized for each of 5 alkyl phosphoric acids.5 alkyl phosphoric acids were simultaneously detected in 30 min.The calibration curves for the analytes were linear in the certain concentration ranges with the limits of detection(LOD) and quantitation(LOQ) of 0.1 μg/L and 0.5 μg/L，respectively.The intra-day and inter-day RSDs were in the range of 2.4%-4.3% and 2.5%-4.5%，respectively.The average recoveries were in the range of 97.3%-98.9% and the RSDs for the method repeatability were 5.3%-10%.With the advantages of excellent selectivity，accuracy，high sensitivity，specificity and good repeatability，the method is suitable for the qualitative and quantitative detections of alkyl phosphoric acids in urine samples exposed to organophosphorus nerve agents.