Abstract: To timely and accurately understand growing conditions of grassland, EOS/MODIS remote sensing data in combination with ground synchronous survey data were used to analyze the monthly variation characteristics of NDVI and the aboveground biomass of three grassland types which were the meadow steppe, typical steppe, and desert steppe in Xilingol grassland. The results showed that monthly grass yield during the growing season could reflect the change of grass growth conditions well using the S curve regression yield estimation model, and present the distribution characteristics of aboveground biomass in all three types of grassland. For the meadow steppe, the range of NDVI and the average grass yield in the grass growing season were 0.208-0.560 and 39.8-168.6 g/m² respectively (dry weight) with the peak value in August; for the typical steppe, the figures were 0.194-0.480 and 33.7-146.2 g/m² (dry weight) with the peak value in July; and for the desert steppe, the figures were 0.130-0.185 and 10.0-29.8 g/m²(dry weight) with the peak value in July.