Abstract: A method for the determination of trace antimony in water samples by aqueous two-liquid extraction-continuous light source graphite furnace atomic absorption spectrometry with ammonium pyrrolidine dithiocarbamate (APDC) as chelating agent, acetonitrile as extraction agent and sodium chloride as inorganic salt was proposed. The optimized aqueous two-phase extraction conditions of Sb³⁺ were as follows: the acidity of the chelation reaction system was pH 4, with 0.5 mL of 2 g·L^-1 APDC reserve solution, 1.6 mL of acetonitrile, and 1.2 g of sodium chloride, and the reaction time was 20 min. Under the experimental conditions, linear relationship between the corresponding absorbance and mass concentration of Sb³⁺ was found in the range of 1.00-20.00 μg·L^-1, with detection limit (3s/k) of 0.048 μg·L^-1. 5.00, 10.00 μg·L^-1 Sb³⁺ standard solutions were determined 10 times, and RSDs of the determined values were 4.6% and 3.3%, respectively. Test for recovery was made by standard addition method on actual samples, giving results in the range of 95.8%-102%. This method was applied to the determination of trace antimony in tap water, river water and lake water, and some trace antimony was found in these environmental samples.