Spatial-temporal variation of soil moisture and its spatial correlations with soybean yield were analyzed with the classical statistics and geostatistics in a black soil sloping farmland. Results showed soil moisture displayed a strong spatial heterogeneity in the sloping farmland, with an effective range varying from 159.3 m to 506.6 m and with rainfall and farming practices. Spatial heterogeneity of soil moisture was enhanced by drought, but could be reduced by farming practices. A significant relationship was found between soybean yield and soil moisture at the seeding stage.