Soil net nitrogen mineralization and nitrification are critical processes that provide nitrogen nutrients for plant growth in degraded Karst ecosystems with limited nitrogen. However, little is known about these processes. In this study, soil samples derived from topsoil (0-15 cm) were collected from the upper, middle, and lower slope positions of four Karst ecosystems-tussock (T),shrub (S),secondary forest (SF) and primary forest (PF), which are a typical vegetation succession series in Karst areas. A soil incubation experiment was conducted to measure the soil nitrogen transformation rates, including net nitrogen mineralization rate, net nitrification rate, and net ammonification rate. The results showed that vegetation types significantly (P<0.01) affected soil NO₃^--N and inorganic nitrogen content, soil net nitrogen mineralization rate, net nitrification rate, and net ammonification rate. In particular, the content of soil NO₃^--N and inorganic N, soil net nitrogen mineralization rate, and net nitrification rate gradually increased along the vegetation succession. The slope position and the interaction between vegetation type and slope position had no significant effect on the monitored variables (P > 0.05). RDA analysis showed that the soil nitrogen transformation rate was primarily affected by the litter nitrogen content, litter C : N, and the content of soil NO₃^--N. However, the litter nitrogen was the main factor affecting the soil nitrogen transformation rate (F=35.634, P=0.002).Our results suggest that vegetation restoration has positive effects on Karst soil nitrogen transformation. The improvement of litter quality (e.g., litter nitrogen content) may be the key factor influencing the soil nitrogen transformation rates over Karst vegetation succession. Therefore, managing litter C: N (e.g., to introduce legumes) may be conducive to the restoration of degraded Karst ecosystems. These findings may serve as a scientific basis for further understanding of soil nitrogen cycling in Karst regions and help facilitate preservation and restoration activities in Karst regions.