Objective To establish a rapid, accurate and sensitive gaschromatography-mass spectrometry (GC-MS) method for the detection ofdichloroacetic acid (DCA) and trichloroacetic acid (TCA) in drinkingwater samples, and to evaluate the performance and practical applicationof the method. Methods The samples were pretreated by liquid-liquidextraction derivatization technology and then analyzed by GC-MS. ${50\mu }\mathrm{L}$ and ${100\mu }\mathrm{L}$ of DCA and TCAstandards were prepared into mother solutions with concentrations of ${5\mu }\mathrm{g}/\mathrm{{mL}}$ and ${10\mu }\mathrm{g}/\mathrm{{mL}}$ ,respectively, and then diluted with methanol to form a series ofstandard solutions with concentration gradients for the establishment ofstandard curves. 1,2-Dibromopropane was used as the internal standardsubstance to prepare an internal standard extract of ${166.1\mu }\mathrm{g}/\mathrm{L}$ tocorrect the error in the sample analysis process. The spike recoveryexperiment was carried out on ultrapure water to evaluate the accuracyand precision of the method, and the detection limit of the method wasdetermined by the signal-to-noise ratio (S/N) method. Finally, 103drinking water samples were tested to analyze the contents of DCA andTCA. Results The linear ranges of the standard curves were $1 \sim {20}\mathrm{{\mug}}/\mathrm{{mL}}$ for DCA and $1\sim {40}\mathrm{{\mu g}}/\mathrm{{mL}}$ for TCA, withcorrelation coefficients $\left({r}^{2}\right)$ greater than 0.99,recoveries of 99.4%~114.3%, RSDs less than 3.541%, and detection limitsof ${0.1\mu }\mathrm{g}/\mathrm{L}$ and ${0.2\mu }\mathrm{g}/\mathrm{L}$ for DCA and TCA, respectively. The contents of DCA and TCA in 103drinking water samples were lower than the national standard limits,with average concentrations of ${0.25\mu}\mathrm{g}/\mathrm{L}$ and ${0.48\mu}\mathrm{g}/\mathrm{L}$ , respectively, and the data werestatistically significant $\left({P<{0.05}}\right)$ . Conclusion The GC-MS method has good linearity, accuracy, precision and sensitivity, and can meet the needs of drinking water safety monitoring. The method was applied to 103 drinking water samples, and the results showed that the drinking water quality met the national standards and was not seriously contaminated by DCA and TCA.