Soil quality is the basis for maintaining stability and functional diversity of the terrestrial ecosystems. While grazing is one of the most widely used methods of grassland resources, its effects on grassland soil quality lack quantitative criteria, and the mechanism of action between the two is unclear. In this study, two seasonal grazing lands in the alpine steppe of the Qilian Mountains were used to investigate the effects and potential mechanisms of grazing on soil quality, combining ecosystem coupling and ecosystem multifunctionality. Results indicated that soil quality index was controlled by grazing rate based on minimum data set (MDS). The soil quality index was the highest at 2.45 red deer month^-1 hm^-2 for winter grazing land, and 0.80 red deer month^-1 hm^-2 for spring and autumn grazing land. Soil available phosphorus, organic carbon, N to P ratio, and soil pH were the major factors driving soil quality in winter grazing land, while soil organic carbon, C to N ratio, and soil pH were the major factors in spring and autumn grazing land, and the soil quality indexes were positively correlated with species richness index (P<0.05) and Shannon-Wiener index (P<0.0001) in the two grazing lands. The coupling degree between plant community species diversity and soil factors were in the range of 0.67 to 0.81 (average degree=0.74), which belonged to middle coordination. The ecosystem multifunctionality index (EMFI) and soil quality index were negatively correlated with grazing rate. The results further highlighted the effects of grazing on soil quality and ecosystem function in two seasonal grazing lands of alpine steppes. Combined with coupling relationships between plant community species diversity and soil factors, this study explored the potential momentum of soil quality fluctuation, which provided a theoretical basis for better protection and utilization of alpine steppes' resources.