Abstract: Altitude variation exerts significant impacts on meadow ecosystem biomass, soil nutrients and their interrelationships. Delving into these mechanisms is crucial for understanding vegetation response processes in extreme environments and provides scientific basis for protecting high-altitude ecosystems. This study focused on the meadow ecosystem of Zheduo Mountain in the southeastern edge of the Qinghai-Tibet Plateau. Eight typical meadow plots with <italic>Carex myosuroides</italic> as the dominant species were systematically selected along an altitudinal gradient. Soil and vegetation samples from different depths were collected to measure aboveground biomass, soil total nitrogen (TN), total phosphorus (TP), organic carbon (SOC), pH, and moisture content. By integrating Analysis of Variance, correlation analysis and grey relational analysis, we investigated how soil nutrients affect meadow biomass under altitudinal variation.The results indicate that: (1) With increasing altitude, the aboveground biomass of meadows, soil TP, and N:P exhibit a unimodal trend of first increasing and then decreasing, whereas soil TN, SOC, C:N, and water content demonstrate a pattern of first decreasing and then increasing; the change in soil C:P was relatively inconspicuous. (2) Nutrients exhibited distinct surface accumulation, with maximum TN, and SOC concentrations in the 0-10 cm soil layer. This surface enrichment weakened progressively with increasing altitude. (3) Nutrient variations in deep soil layers (10~20 cm) have a more pronounced regulatory effect on meadow biomass than those in surface soil layers (0~10 cm). Specifically, soil TP in the 10~20 cm layer is a key positive factor influencing aboveground meadow biomass, while soil SOC in the same layer is a critical positive factor affecting belowground meadow biomass. In contrast, the pH value of surface soil has minimal influence on meadow biomass. This study elucidates altitudinal response mechanisms between soil nutrients and biomass in Zheduo Mountain meadows, identifying the core driver of biomass variation. These findings provide scientific support for ecological conservation and sustainable management of alpine meadow ecosystems.