Grasslands are areas where the vegetation is dominated by grasses and supports indigenous or introduced vegetation and has potential to be grazed (Adams et al. 2009). Grasslands occupy approximately 51% of terrestrial surface of the earth (Prentice et al. 1992) and the important source of atmospheric carbon dioxide (CO2) sequestration. During photosynthesis the vegetation in grassland assimilate atmosphere carbon into its tissues and part of it is added to soil as soil organic carbon (SOC). Nepal total grassland areas are estimated to cover about 1.75 million ha or nearly 12% of Nepal total land area (LMP 1993). Nepal’s largest grassland about 5.64% of total area of the country lies at higher elevation (LRMP 1986). This study was conducted to know the variation in SOC within different altitude grasslands of Langtang National Park (LNP). Soil samples were collected at different altitude: 1500- 2000m, 2001- 2500m, 2501-3000m, 3001- 3500m and 3501- 4000m. The soil samples were collected at different depths in each grassland i.e. 0 – 10 cm, 10 – 20 cm and 20 – 30 cm. The maximum SOC was found in grassland at altitude 3001 m- 3500m. The lowest was SOC was found in grassland at altitude 3051m – 4000m. Correlation analysis between altitude and SOC shows that SOC is positively correlated with altitude with correlation coefficient 0.603 (significant at P<0.05 level). But SOC decreases sharply in treeline with negative correlation (Significant at P<0.05).