n order to study water-rock interaction in the aeration zone and the formation of groundwater during precipitation recharge, four soil samples were collected from Xinchang, northwest China. They were immersed in deionized water at a solid-liquid ratio of 1:2 for 28 days. The variation of different ion components in the solution was analyzed. The results show that as the leaching time increases, the different ion contents of the soil solution increases. It is indicated that during the recharge of groundwater by precipitation, the leaching of precipitation through the aeration zone will cause some materials in the aeration zone to be transferred to the water. The chemical characteristics of the water will change and leaching plays an important role in the formation of groundwater.