【Objective】Soil erosion is a major factor causing soil degradation and crop productivity reduction in the northeast black soil region. However, the in situ systematic and quantitative assessment of the effects of erosion on soil quality and crop productivity remains unclear. 【Method】A long-term field experiment on erosion-productivity relation was set up at Heshan Farm, Heilongjiang Province in 2005 based on comprehensive effects of erosion and tillage on soil profile. The experiment was a two-factor completely randomized block design with simulated erosion depth (8 levels of 0, 10, 20, 30, 40, 50, 60, and 70 cm) and fertilization (no fertilization and fertilization), totaling 16 treatments with 3 replications per treatment. In 2022, a series of soil physicochemical properties [bulk density (BD), soil water content (SWC), clay content, pH, soil organic C (SOC), alkali-hydrolyzed N (AN), Olsen-P (AP) and available K (AK)] and biological properties [microbial biomass C and N (MBC, MBN), catalase, urease, ?-glucosidase, cellulase activity] in 0-20 cm soil layer and corn yield were measured after 18 years of the setup. 【Result】1) Soil clay content, SOC, AN, AP, MBC and cellulase activities decreased significantly with the increase of simulated erosion depth, while soil BD and AK increased significantly. Also, fertilization significantly decreased soil BD, pH, AK, and catalase activity, but increased clay content, SOC, AN, AP, and the activities of urease, ?-glucosidase, and cellulase. Interestingly, fertilization weakened the correlation between soil urease activity, BD and other physicochemical properties. 2) Simulated erosion resulted in significant reductions in soil quality and corn yield, the decrease mainly occurred before the erosion depth of 40 cm. Soil quality index decreased by 28.1% for the unfertilized treatment and 26.7% for the fertilized treatment, and yield loss was 45.8% for the unfertilized treatment and 11.7% for the fertilized treatment at 40 cm of erosion depth. Additionally, fertilization increased the soil quality index by 7.0% and corn yield by 3.0 fold. 3) The main factors affecting soil quality under simulated erosion were cellulase activity, MBC and AN for the unfertilized treatment, and cellulase activity, MBC, AP for the fertilized treatment. Also, the main factors affecting corn yield under long-term simulated erosion were AN for the unfertilized treatment and AP for the fertilized treatment. 【Conclusion】These results quantified the degree of soil erosion on soil quality and productivity and clarified the major factors affecting soil quality and productivity in black soil, and can serve as reference for the restoration of degraded black soil.