The rate of soil nitrogen mineralization can determine the supply capacity of available nitrogen in forest soil, but it is not yet fully understood in the succession process of secondary forests on the Loess Plateau. This study selected nine plant communities from five succession stages (herbaceous community stage, shrub community stage, pioneer forests community stage, mixed forest stage and climax forest community stage) in the secondary succession forest area of Huanglong Mountain area on the Loess Plateau as sample lands. The soil nitrogen mineralization rate was measured, and the soil physicochemical properties, litter nutrient characteristics, soil enzyme activities and their impact on nitrogen mineralization were analyzed. The results revealed a continuous accumulation of soil organic carbon and nitrogen with the progression of succession, and the soil nitrate and ammonium nitrogen contents also gradually increased. Litter nutrients and soil enzyme activities changed significantly along with succession. The soil nitrification rate increased by 71.73% from the herbaceous community stage to climax forest community stage, while the ammonification rate remained negative and continued to increase negatively with succession. The soil net mineralization rate increased from (0.16±0.06) mg kg^-1 d^-1 in the herbaceous community stage to (0.31±0.08) mg kg^-1 d^-1 in the mixed forest stage, but decreased from the mixed forest to the climax forest community stage. Soil physicochemical properties (path coefficient -0.530) and enzyme activities (path coefficient-0.268) influenced the rate of nitrogen mineralization directly. The effect of litter nutrients on the nitrogen mineralization rate stemmed from both direct influence (path coefficient -0.283) and indirect effect through the regulation of soil physicochemical properties and enzyme activities (path coefficient -0.315). These results can contribute to our understanding of the soil nitrogen cycle during vegetation succession on the Loess Plateau, and help with the sustainable forest management.