Abstract: Quantitative and accurate description of the complex geochemical interaction of landslide water-soil interaction system is particularly important for the research on geochemical interaction of micro scale. In this study, purple soil samples were collected from the Shiliushubao landslide near the Three Gorges. Ca2+ was selected as the characteristic ion in the simulation solutions. Indoor circulatory soil column simulated experiments were conducted with deionized water and calcium solution with pH = 4, 7, and 10 under the conditions of the flow speed of 20 ml/min, indoor temperature of 17 + 2℃, the proportion of soil quality and solution volume of 1:5. PHREEQCE was used to study the water-soil interaction in the experiment and analyze the hydrogeochemical behavior of Ca2+. The results show that the existence of Ca2+ in the solution restrained the solution of calcareous cement and the production of clay minerals, enhanced ion-exchange action. The production of clay minerals and ion-exchange action make soil porosity become small, particles become close and the landslide gets stable. It is of an important theoretical significance and applicable value for studying mechanism and process of water-soil geochemical interaction of the Shiliushubao landslide.