Abstract:Qinghai Province is one of five largest pasturing areas and ranks four th in China. It is of great importance to learn the growth status of grass in t ime to eco environment protection and sustainable development of stock raising. Based on the data of fresh grass weight per square meter from 22 eco environmen tal monitoring stations　(which were established by Qinghai Meteorological Bureau in 2002) during grass growing season from 2003 to 2004, as well as the same p eriod of MODIS data, by preprocessing，cloud detecting, EVI computing and monthl y maximum EVI compositing, MODIS EVI data were obtained corresponding to grass output data. The relationship between grassland output and EVI was established a ccording to the grass growing season and grassland type. The results show that g rassland output have a good correlation with MODIS EVI, and it can be better des cribed by the exponential function. Furthermore, the grassland output model base d on the grass growing season is better than that of based on grassland type.