To establish a method for measuring methylmercury and other mercury species in aquatic products by HPLC-AFS. MethodsThe samples were extracted and centrifuged after hydrochloric acid ultrasoundtreatment. 5% of Acetonitrile, 4.62g/L ammonium acetate and 1.2g/L cysteine solution was used as mobile phase. Then the samples, being tested with AFS after C18 seperated, were quantitatively determined by external standard method. There was no need of oxidization or ltraviolet photolysis. ResultsThe best linear range of methylmercury, ethylmercury and inorganic mercury was 0-50μg/L with correlation coefficients above 0.9990, the detection limit was 0.5-1.5μg/L, the precision relative standard deviation was less than 6%, and recovery of spiked samples was 78%-120%. Methylmercury measurement of standard substance in fish was within the reference range.ConclusionThis method was simple, sensitive, accurate and suitable for the determination of mercury species in aquatic products.