In order to quantitatively analyze the relationships between the biomass and the environmental factors for the three types of alpine grasslands (alpine marsh meadow, alpine meadow and alpine steppe) in the permafrost regions of Tibetan Plateau, six active layer plots in the plateau were selected. The results show that the underground biomass contributes a large percentage of the total biomass in the alpine grasslands, which concentrates in the depth range from 0 to 10 cm. The factors affecting total biomass and underground biomass rank in the order: soil salinity, soil moisture content and air temperature. However, the factors affecting the aboveground biomass rank in the order: soil moisture content, soil salinity and air temperature. It is also observed that the soil temperature has a negative correlation with biomass. Furthermore, with permafrost degradation, the soil temperature significantly increases, the soil moisture content decreases gradually and the soil salinity continuously increases throughout different soil depths of the active layer (10~50 cm); As a result, a retrograde succession from alpine marsh meadow, alpine meadow to alpine steppe occurs in the alpine grasslands vegetation, and then a obvious decreasing trend will occur for the total coverage and biomass.