Ultrasonic assisted extraction coupled with high performance liquid chromatography-inductively coupled plasma mass spectrometry was developed for the determination of mercury speciation in aquatic products. Using ultrasonic assisted extraction for sample in HCl + L- cysteine system, with 10 mmol/L ammonium acetate +0.10% L- cysteine buffer and methanol (982) system consisting of mobile phase, and detected the content of inorganic mercury and methyl mercury and ethyl mercury by high performance liquid chromatography- inductively coupled plasma mass spectrometry. The detection limits (3S/N) of inorganic mercury, methyl mercury and ethyl mercury were 0.18, 0.09, 0.15 ng/mL, respectively. The correlation coefficient (R) of the regression equation of the standard curve was above 0.999. Inorganic mercury and methyl mercury, ethyl mercury were spiked in actual samples, the rate of recovery was 78.5%～96.8%, the relative standard deviation (RSD)≤3.0%. The standard substance was detected by this method, and the measured value was consistent with the standard value. The method is accurate, reliable, simple, rapid and accurate. It can be applied to the analysis of mercury speciation in aquatic products.