Accurately assessing grassland health necessitates quantifying changes in plant community diversity and soil physicochemical properties during the successional processes of vegetation degradation and restoration. This study classified degradation into three stages (light, moderate, and heavy) and restoration into two stages (enclosure <= 5 years and enclosure >5 years). We conducted a quantitative assessment of vegetation characteristics and the dynamics of soil carbon, nitrogen, and phosphorus across different degradation and restoration stages, utilizing 30 pairs of grazed and exclosure control plots across the watershed. Our results revealed significant variations in vegetation cover and species richness along the degradation and restoration gradients. Aboveground biomass and vegetation cover declined progressively with increasing degradation intensity. Soil nutrients, including SOC, TN, and TP, exhibited a pronounced "surface accumulation" pattern, with the highest concentrations in the topsoil (0-10 cm). Significant differences in SOC, TN, and TP were observed among degradation stages in surface soils, while bulk density (BD) and pH values showed relatively little variation. Soil water content and TP differed significantly in the topsoil among restoration stages. Enclosure enhanced aboveground biomass and species richness, but species diversity declined when enclosure duration exceeded five years. Although soil nutrient contents changed after enclosure, the relative rates of change in soil stoichiometry remained largely unchanged. These findings highlight the importance of integrating vegetation and soil parameters for a comprehensive assessment of grassland health and restoration effectiveness.