Abstract: The contents of F-, Cl-, NO2-, NO3- and SO42- in semi-seawater from the Pearl River estuary were determined by ion chromatography. The AS 23 anion-exchange column was used for separation, and a mixture of 6.0 mmol·L-1 Na2CO3 and 1.2 mmol·L-1 NaHCO3 was used as eluent. Inhibitory conductivity detection was adopted in the determination. Linearity ranges of F-, Cl-, NO2-, NO3- and SO42- were found between 0.108 2-1.536 mg·L-1, 200.1-3 029 mg·L-1, 0.044 2-0.602 4 mg·L-1, 0.527 4-7.569 mg·L-1 and 10.84-151.4 mg·L-1, with detection limit (3S/N) of 0.02, 0.05, 0.003, 0.03 and 0.10 μg·L-1 respectively. The proposed method was applied to the determination of the 5 anions in simulated seawater samples, values of recovery found were in the range of 80.5%-115.1% and values of RSD′s (n=7) found were less than 5%.