Climate change and human activities have resulted in grassland degradation on the Qinghai-Tibetan Plateau, enhancing grass-livestock imbalance and restricting the sustainable development of pastoralism on the plateau. Summer supplementary feeding is regarded as an important way to achieve sustainable development goal due to accelerated production rate, enhanced slaughter rate, and reduced grazing pressure. However, the impact of summer supplementary feeding of yaks on ecosystem functions in grasslands remains unclear. To address this issue, we established a yak grazing experiment in an alpine meadow, including summer supplementary feeding grazing (FG), traditional heavy grazing (TG), and grazing prohibition (NG). Our results indicated that summer supplementary feeding alleviated the decline in plant α-diversity caused by traditional grazing. Both summer supplementary feeding and traditional grazing reduced plant biomass. The traditional grazing had lower surface soil pH and nitrate nitrogen compared to grazing prohibition, while summer supplementary feeding weakened these effects. Summer supplementary feeding significantly decreased soil organic carbon in the 20-30 cm soil but increased total phosphorus content in the surface soil. The study suggests that summer supplementary feeding grazing has the potential to reduce the pressure of traditional grazing and provides important scientific evidence for the protection and management of alpine ecosystems in the Qinghai-Tibetan Plateau.