[Objective] The effects of erosion on the surface soil of erosion gullies in sloping cropland soils in a black soil area were studied in order to provide theoretical support for the rational utilization of soil resources and regional soil and water conservation work in black soil areas. [Methods] The study was conducted on erosion gullies with different degrees of development in Yanshou County, Harbin City, Heilongjiang Provicne. Particle size distribution and water storage properties of soil on the slope, at the bottom of the gullies and at the head of the gullies were quantitatively described. [Results] ① Soil bulk density, maximum water-storage capacity, maximum water-retention capacity, total storage capacity, dead storage capacity, and maximum effective storage capacity at different depths were significantly different (p＜0.05). As soil depth increased, soil bulk density also increased, and water-storage, water-retention, and effective water storage capacity decreased. Each layer had a maximum water-storage capacity of about 90% of its saturated capacity, and the effective water utilization rates were 44.79% and 41.87%, respectively. The development of erosion gullies had a clear influence on effective soil water. ② The infiltration characteristics generally showed that the initial infiltration rate＞the 30-minute infiltration rate＞the stable infiltration rate. As soil depth increased, the infiltration characteristics of the three indicators decreased between gully A₂ and A₄ for different erosion degree gullies. In the 20—40 cm layer, the infiltration characteristics of gully A₁ to A₄ followed the order of CK (control group)＞ gully A₁＞ gully A₄＞ gully A₂＞ gully A₃. Infiltration initially declined and then increased. With the development of the erosion gully, soil infiltration decreased and then increased. ③ The development of erosion gullies was the main reason for the change in clay content. The percentage of clay in the 0—40 cm layer tended to increase first and then decrease. The percentage of sand in the 0—20 cm layer tended to decrease first and then increase, showing a trend toward increased coarseness. ④ The soil degradation index followed the order of gully A₁＞ gully A₂＞ gully A₃＞ gully A₄ in the 0—20 cm layer. Soil degradation increased with the development of erosion gullies. Soil degradation was most severe in gully A₄. [Conclusion] The differences in soil profiles was the main reason for the differences in physical properties of black soil. Soil water-holding capacity in the 0—20 cm layer was weakened and soil degradation became severe as erosion gullies developed.