Abstract: A method for the determination of 3 biocides, including iodopropynyl butylcarbamate, chlorothalonil and triclosan, in waterborne coating by gas ghromatography-mass spectrometry was proposed. The waterborne coating sample (1 g) was taken, and 500 μL of 1 000 mg·L^-1 n-eicosane (internal standard) solution was added. The mixture was diluted to 10 mL with ethyl acetate, mixed well, and extracted by ultrasound for 30 min. After cooling, the above solution was centrifuged for 20 min at 4 000 r·min^-1, and the supernatant was taken for determination. The target compounds were separated on HP-5ms quartz capillary column by column heating procedure, detected by mass spectrometer, and quantified by internal standard method. It was shown that the linear ranges of the standard curves of 3 target compounds were 0.1-100 mg·L^-1, with detection limits (3S/N) in the range of 0.033-0.098 mg·kg^-1. Test for recovery was made on the negative sample at 3 conecntration levels, giving results in the range of 87.1%-103%, and RSDs (n=7) of the determined values were less than 5.0%. This method was applied to analysis of 10 actual samples. Chlorothalonil and triclosan were not detected, and iodopropynyl butylcarbamate was detected in one sample, with detected amount of 760.7 mg·kg^-1.