Based on AVHRR GIMMS NDVI and MODIS NDVI data,spatial-temporal variations of the grassland coverage in the Loess Plateau from 1982 to 2014 were simulated using dimidiate pixel model,and the relationship between grassland coverage and climate factors was analyzed at grid scale. The results showed that average annual grassland coverage from 1982 to 2014 was 42.5% in the Loess Plateau,and the grassland coverage had increased over the past three decades. Besides,the area of low coverage grassland rapidly declined,and high coverage grassland developed fast. There was significant spatial difference of grassland coverage,and the grassland coverage of the southeast of the study area was higher than that of the northwest. Before the project of returning farmland to grassland (19821998),there was no significant change of grassland coverage in most regions of the study area. However,since the implementation of large-scale vegetation construction from 1999,the annual mean grassland coverage of the study area has increased significantly at a rate of 1.76%, especially in northern Shaanxi Plateau,Taihang-Lvliang Mountains,where significant increase in grassland coverage has been seen. The green for grain project has greatly improved the vegetation. As a whole,there was no significant correlation between grassland coverage and annual precipitation and temperature,but significant spatial difference was significant. The grass growths were sensitive to precipitation.