Soil moisture is the key factor restricting vegetation growth in Pisha sandstone area, and Pisha sandstone area is also located in semi-arid area, so it is clear that soil moisture migration in Pisha sandstone area is the basis for afforestation selection. In order to reveal the dynamic change process of soil moisture of different tree species in the Pisha sandstone area, based on the fixed-point monitoring from July to September 2024, the temporal and spatial changes of soil moisture at the depth of 0-100 cm of three plantations (pure caragana forest, pure pine forest, and mixed forest of C. caragana × Pinus tabuliformis) in the Pisha sandstone area were analyzed, aiming to understand the water changes of C. caragana and P. tabuliformis under different afforestation modes in the Pisha sandstone area, and to provide reference ideas for the selection of afforestation tree species. The results showed that: (1) The soil moisture content of the mixed forest of Caragana × Pinus tabuliformis was the highest (25.89%), followed by the pure P. tabuliformis forest (24.28%), and the lowest (16.46%). (2) With the scale of rainfall from small to large, the depth of soil moisture replenishment was 10 cm and 60 cm, respectively, and when the rainfall scale was heavy rain and heavy rain, the soil moisture at a depth of 0-100 cm was supplemented. Under different rainfall scales, the soil moisture increment of pure caragana forest was the highest, followed by P. tabuliformis, and the soil moisture increment of C. caragana × Pinus tabuliformis mixed forest was the lowest. (3) When the rainfall grade was heavy rainfall, the three stands responded to the rainfall after the rain in the 0-50 cm soil layer, and the soil moisture content decreased slowly on the second day, and the water migration lag showed in the 50-100 cm soil layer.