Global climate change has significantly impacted biodiversity and ecosystem functions. Although numerous controlled experiments have been conducted to examine the effects of global climate change on ecosystem functions, the understanding of how the snow cover affects ecosystem functions is still insufficient. This study focuses on the alpine meadow ecosystem in northwestern Sichuan. We explored the comprehensive impact of snow cover thickness changes on biodiversity and multiple ecosystem functions based on a long-term snow experiment, aiming to reveal the role of snow cover in maintaining grassland ecosystem multifunction. The results show that snow cover significantly altered the community species richness with highest species richness in snow remove treatment, but had minor effects on Simpson diversity, evenness index, functional diversity and CWM (community-weighted means) traits. In addition to aboveground productivity, snow cover had significant effects on ecosystem functions, including belowground productivity, coverage, water holding capacity, soil total carbon, nitrogen and phosphorus. However, the effect of biodiversity, including taxonomic diversity and functional diversity, on ecosystem functions is relatively limited. Results from the SEM analysis indicated that snow cover directly promotes grassland multifunctionality and had directly negative and positive effects on functional diversity and pH, respectively. However, snow cover did not affect multifunctionality through these variables. This study not only provides a new theoretical perspective for understanding the impact of snow cover changes on alpine meadow ecosystems but also offers a scientific basis for the development of targeted grassland management and ecological protection strategies in the future.