The distribution characteristics of the topsoil (0-20cm) labile organic carbon of alpine grassland ecosystem at the south slope of Gongga south mountain-Laguigangri mountain were studied. The results showed that, the average content of the topsoil (0-20cm) labile organic carbon was (2.4986±0.7864) g/kg, accounting for (12.7926±21.00)% of the topsoil organic carbon in alpine grassland ecosystem at the south slope of Gongga south mountain-Laguigangri mountain. With increasing altitude, the distribution characteristics of the topsoil (0-20cm) labile organic carbon and organic carbon lability were decrease→increase within the altitude range of 4424-4804m. The key environmental factors influencing the content of topsoil labile organic carbon were overground biomass, biomass of underground 0-10cm and 30-40cm, moisture of underground 20-30cm, soil bulk density of underground 0-20cm and 20-40cm, and soil total Nitrogen content. However, the key environmental factors for the topsoil (0-20cm) organic carbon lability were vegetation coverage, 20-30cm belowground biomass, 0-10cm,10-20cm and 20-30cm underground soil moisture, soil organic matter, soil labile Potassium and soil total Nitrogen content.