Abstract: Arsenic is one of the indicators for the total emission control in China. The toxicity of different forms of arsenic varies greatly. Therefore, the study of arsenic forms is of great significance. The current research on arsenic forms mainly focused on the aquatic products, while the study on arsenic forms in the interstitial water of sediment is few. Arsenic forms and pollution in sediment pore water are important environmental indicators, which can affect the living organisms and indirectly affect the human health. High performance liquid chromatography-atomic fluorescence spectrometry (HPLC-AFS) was used, with diammonium hydrogen phosphate as the mobile phase, hydrochloric acid as the carrier current and potassium borohydride as the reducing agent. Under optimized test conditions, arsenite As (Ⅲ), dimethyl arsenic (DMA), monomethyl arsenic (MMA) and arsenate As (Ⅴ) were determined. The linear correlation coefficients of standard curves were greater than 0.999 1. The detection limits of four arsenic forms were 0.22~0.43 μg/L. The relative standard deviations (RSDs) were less than 4.0%, and the recoveries of each component were 89.0%~103.0%. The results showed that the method is accurate, reliable and easy to operate, and can be used for the determination of arsenic speciation forms in the interstitial water of sediment.