By using the MODIS 16-day composite NDVI and meteorological data from 2001to 2017in Chifeng, Inner Mongolia,the temporal and spatial variations of natural grassland NDVI and its response to climate factors were comprehensively studied.The results showed that the annual NDVI in the study area increased significantly in the last 17years(P<0.05),at a rate of 0.002 0·a~(-1).The monthly NDVI showed a single peak trend with the peak in July(0.759 4)and August(0.726 2)annually.There was a significant positive correlation between NDVI of natural grassland and precipitation from May to September in the study area,but no significant positive correlation between NDVI and average temperature.The effect of precipitation on NDVI of natural grassland in the study area was more significant than that of temperature.The precipitation of the growing season(June,July,and August)was significantly positively correlated with NDVI(P<0.01)and the simple correlation coefficients were 0.730,0.724,0.789,and 0.782,respectively.The precipitation of May and September were also significantly positively correlated with NDVI(P<0.05).There was no significant positive correlation between monthly temperature and NDVI(P>0.05).