A sensitive and reliable method was developed for the quantitative determination of three metabolites of trichloroethylene，e.g.monochloroacetic acid(MCA)，dichloroacetic acid(DCA) and trichloroacetic acid(TCA)，in urine sample.Three metabolites were derivatized by ethanol esterification in the presence of ferric chloride acted.Effects of esterification temperature,esterification time and amounts of ferric chloride and ethanol were discussed，and the optimization conditions were using 4 mL urine sample mixed with 1.05 mmol ferric chloride and 2.0 mL ethanol to derivatize for 50 min in 90 ℃ water bath.The three ethyl esters in sample were simultaneously determined by derivatization gas chromatography coupled with electron-capture detection after extracted with 2 mL hexane.The method showed good linearities in the ranges of 40-2 400，20-1 000 μg/L and 10-500 μg/L for monochloroacetic acid，dichloroacetic acid and trichloroacetic acid，with correlation coefficients of 0.999 8，0.999 3 and 0.999 2，respectively.The average spiked recoveries of three metabolites in urine sample were 104%，109%and 106%，with their detection limits(S/N=3) of 4.67，1.32 and 0.27 μg/L，respectively.With the advantages of simplicity,requirements for relatively moderate reaction condition and non-corrosion reagents,the method was applied in the quantitative analysis of three metabolites in the urine samples from workers exposed to the trichloroethylene contaminant with satisfactory results.