Abstract: Grasslands not only support animal production, but also play an important role as an ecological safety barrier and they maintain herders’ livelihood as well as inherited culture. However, a series of ecological problems are becoming more and more serious because of increasing grassland degradation. The economic valuation of the grassland ecosystem service function will help conservation and rational development of grassland resources in China. Costanza’ evaluation method for ecological services value was widely adopted abroad but this method cannot fully reflect the intrinsic characteristics of grassland ecosystems. Based on the functions of ecology, production, and living systems of grassland ecosystems, the contribution rate of the top 12 items for ecological services function of grassland ecosystems (water storage, erosion control, nutrition cycling, waste treatment, resort sand and dust, biological control, release O₂, fixation CO₂, cut SO₂, recreation, culture, and animal production), were chosen for this study of a comprehensive consideration of regional differences, spatial heterogeneity, and difference of economic development levels of different areas. The evaluation index system and models of grassland ecological services value were established based on the theory of ecological economics. The values of grassland ecosystem functions of the northern Tibet region were evaluated using this method.