[Objective] The dynamic change characteristics of soil water under different rainfall patterns were studied, in order to provide theoretical basis for judging the stability of community structure and optimizing the community structure.[Methods] Taking the soil of different depths in typical aerial seeding Hedysarum leave shrub land in Mu Us sandy land as the research object, The watchdog automatic water monitoring system was used to monitor the dynamic change of soil moisture content in different depths continuously. The temporal and spatial changes of soil moisture in 10, 30, 50, 70, 90 and 110 cm soil layers under different rainfall events were studied, and the characteristics of soil moisture infiltration, redistribution and water supply were analyzed.[Results] ① The change of soil moisture content in 0-110 cm depth of Hedysarum leave community was affected by rainfall, and had obvious vertical characteristics. The soil water content in 10 cm depth was changed greatly, that in 30 cm depth was changed weakly, and that in 50 cm depth was stable. ② The soil moisture at the depth of 10 cm showed an obvious response to rainfall and temperature. The rainfall intensity and initial water content showed a greater impact on the recharge of shallow soil and a certain impact on the infiltration depth. The response of the soil layer below 30 cm to rainfall lagged behind with the increase of depth. The soil layer between 30 to 50 cm was mainly affected by initial water content and rainfall, while the change of water content below 50 cm was mainly affected by rainfall. ③ The rainfall of > 8.8 mm had replenishment effect on the soil layer of 10 cm and below, and the rainfall >40 mm could reach at least 110 cm soil depth through precipitation redistribution.[Conclusion] The root system of Hedysarum leave community is mainly distributed at 0-40 cm soil layer. The rainfall of >8.8 mm can be effectively used by poplar and firewood community. The rainfall of >40 mm can recharge groundwater effectively, which is conducive to the stability of community structure and coping with the dry months with less rainfall in the early stage of vegetation growth in the next year.