Both freeze-thaw cycles and vegetation cover changes significantly influence slope runoff and sediment yield in permafrost regions. Nevertheless, their synergistic mechanisms remain inadequately quantified and poorly understood. Through simulated rainfall experiments conducted on slopes in the source region of the Yangtze River, this study investigated the impacts of vegetation cover variation combined with soil freeze-thaw processes on runoff and sediment yield from typical alpine meadows and alpine steppes. The results indicate that: (1) The three factors of vegetation type and coverage, as well as rainfall intensity, jointly shape the relationship between precipitation runoff and sediment. Alpine meadows showed stronger erosion resistance than alpine steppes. (2) The freeze-thaw process of soil dominated the runoff and sediment generation: Runoff volume across varying vegetation coverage followed the order: autumn freezing period > spring thawing period > summer thawed period. However, sediment yield was highest during the spring thawing period, followed by the autumn freezing period and summer thawed period. (3) For higher vegetation coverage, freeze-thaw effects had a greater impact on runoff than on sediment yield; on the contrary, under low-coverage vegetation, the freeze-thaw process influenced sediment yield more than runoff; These findings provide theoretical guidance for achieving integrated soil erosion regulation goals in alpine grassland ecosystems within the Qinghai-Tibet Plateau under climate change.