Yulin is a typical ecologically fragile area in China,and its vegetation ecosystem is so fragile that could be vulnerable to climate change and human activities. In this study, the linear trend analysis, correlation and buffer analysis were used to analyze the spatial and temporal change of Normalized Difference Vegetation Index ( NDVI) and its relationship with climate change and human activities based on MODIS NDVI data from 2000 to 2015 and annual temperature and precipitation data from 2000 to 2014. Result are as follows :① NDVI values and vegetation coverage in Yulin were low, and NDVI had a linear annual growth rate of 0.009 6 from 2000 to 2015. The proportion of areas with growth trend accounted for 97. 06% of the total area,but the area with decrease trend was small, which was mainly related to human activities and distributed in the southwest mountainous area,urban neighborhood and river valleys in central and eastern Yulin ;② NDVI had mainly a negative correlation with temperature,but mainly a positive one with precipitation,which revealed that rainfall is the main factor affecting vegetation growth; ③ NDVI change process indicated that the intensity of human activities in city-level buffer was higher than that in county-level buffer. Human activities in city-level buffer affected strongly the area within 5 km,they were decreased in the area from 5 km to 9 km,and there were no effects of human activities in the area further than 9 km.