Abstract: The paper aims to study whether nanometer-grade sepiolite could be used to remove heavy metal cadmium in aquatic environment. Under the condition of a laboratory simulation, we constructed 2 aquatic ecosystems with the exposure levels of Cd 50 μg/L and 100 μg/L respectively, and compared the effects of 2 kinds of sepiolite (common particle size and nanometer size) on the removal of heavy metal cadmium in fishery water and aquatic products. The results showed that: within 10 days, Cd had a bio-concentration process from water body to fish body; we then used the sepiolite powder of 0.03 g/L to sprinkle the water body, and discovered the adsorption removal ability of nanometer sepiolite to Cd was superior to that of common particle size, the adsorption stability was also better; after adsorption removal, the content of Cd in the muscle of edible parts of fish body was lower than that before the treatment (on the 10th day), but it was not significant, and the high concentration treatment group still exceeded the relative standard; although sepiolite especially the nanoparticle size sepiolite could effectively remove Cd in the fishery water, but the bio- concentration and accumulation effect resulted in the non-significant decrease of the Cd content in the fish body. The study suggests that: the Cd polluted water body should be remedied before the start of fishery aquaculture in order to meet the fishery water quality standard, so as to ensure the quality and safety of aquatic products for marketing.