Abstract: The method for determination of mercury speciation analysis in seafood by HPLC-ICP-MS has been established. Using hydrochloric acid extract, C18 Chromatography column (4.6 mm×150 mm), mobile phase is 5% methanol-0.06 mol·L^－1 ammonium acetate-0.1% cysteine , the linear range for three mercury species are all between 0 and 100 μg·L^－1, the linear coefficient(r) are all more than 0.999 0, detection limits are between
0.5—0.8 ·L^－1; the relative standard deviations (RSD) for the determination of three mercury species are all less than 5%; the recoveries of different concentrations of mercury compounds: inorganic mercury is 72.5%—89.8%, methylmercury is 99.2%—117.6%, ethylmercury is 93.1%—111.2%; determination of mercury speciation analysis in fish reference material (GBW10029) and human hair reference material (GBW09101B) are all in the scope of standard values. The International Comparison in FAPAS of methylmercury, the result of Z score is 1.0. The experiments show that: this method had simple pre-treatment method, broad line-arrange, good accuracy and precision, it has been applied for determination of mercury speciation in aquatic product.