Taking the grassland sandy soil of East Wuzhumuqi as the research object, and simulating mercury deposition, orthogonal experiment was adopted. The effects of soil/solution ratio, initial mercury concentration, pH, humic acid and concentration of sodium nitrate on the adsorption of grassland sandy soil for HgCl₂ were studied through the method of orthogonal experimental design. The mercury determination in soil were determined by water bath digestion atomic fluorescence spectrometry. The results showed that the smaller the soil/solution ratio was, the larger the initial mercury concentration and the stronger the soil adsorption capacity. The amount of mercury adsorbed by soil was affected by the amount of humic acid, the concentration of sodium nitrate and solvent pH, and the adsorption amount increased first and then decreased with the increasing of the above three factors. When the solvent pH was 7.5, the concentration of exogenous humic acid was 0.6 mg/g and the concentration of sodium nitrate was 0.08 mg/L, the soil adsorption capacity reached the maximum. The factors affected the adsorption of sand for HgCl₂ followed the order of initial mercury concentration > soil/solution ratio > pH > sodium nitrate concentration > humic acid content. Fitting experimental data showed that the accumulation behavior of mercury in sandy soil accorded with the adsorption kinetics process and well correlated with Lagergren quasi-second-order kinetic model, which indicated that the adsorption process was mainly chemical adsorption and the adsorption process was irreversible.