Abstract:Rainfall is the main source of water in arid and semi-arid areas. Rainfall, rainfall duration and rainfall intensity all affect rainfall water infiltration, which in turn affects the replenishment of rainfall to different soil layers under the surface. It is important to study the dynamic response of soil moisture in different soil layers to different rainfall patterns in arid and semi-arid areas to reveal the key elements of water and soil, grassland desertification prevention and climate change responses. Through the continuous observations of the rainfall and the volumetric water content data of 5, 15, 30, 60 and 100 cm below the soil surface in the Xilin Gol League, and the changes of soil moisture in each soil layer and their response to the rainfall events were studied. The results showed that for grassland in arid and semi-arid areas, rainfall could significantly affect the soil moisture in soil layer of 5-60 cm; with the deepening of soil layer, the soil moisture increment caused by the same rainfall process showed a decreasing trend. The increase in soil moisture in 0-10 cm and 10-20cm soil layer was obvious, while if the rainfall was less than 3, 6, 20, 50 mm, water could not reach the 5, 15, 30 and 60 cm soil layers. The heavier rainfall intensity and the higher soil moisture content before rainfall were favorable for the rain water infiltration. The increase of soil moisture in 5-60 cm soil layer had significant or extremely significant linear relationship with rainfall intensity, initial soil moisture content and their interaction. But there was no significant linear relationship in 100 cm soil layer. The soil moisture increments in the 30 and 60 cm soil layers occurred only when the rain-free day interval was extremely short or the rainfall was very large.