Panzhihua City is located in the confluence area of the Jinsha River and the Yalong River, which is an ecologically vulnerable region in the upper reache of the Yangtze River and a key area for implementing the “natural forest protection project” and the “returning cultivated land to forestry project” in China. Based on the MODISNDVI data from 2001 to 2010, meteorological data and other ancillary data in the same period, in this paper we analyzed the spatial and temporal variation of vegetation NDVI and its relationship with climatic factors and human activities by using the methods of maximum value composites, trend analysis and linear regression analysis. The results showed that the vegetation cover in the Panzhihua City was high and belonged to the high vegetation cover area. On the interannual scale, the vegetation cover showed an upward trend, with a growth rate of 0.02/10 a. During a year, NDVI was peaked in September and had the lowest value in March. The vegetation cover showed a horizontal spatial distribution pattern of “High in the north and Low in the south” and also showed significant differences in the vertical direction. The vegetation cover in the study area reached the maximum at the altitude range of 2 000 m-3 000 m and the slope range of 30 °-40 °, respectively. Constrained by hydrothermal conditions, the vegetation cover on shady slopes (0°-45°, 315°-360°) was higher than sunny slopes (135°-225°) , and the NDVI had the lowest value in the flat areas. For the entire study area, the areas with degraded vegetation and the vegetation greening areas accounted for 0.7% and 44.4% of the total area, respectively. The greening areas were much larger than that of the degraded area. Over the 10 years, the vegetation was more affected by temperature than precipitation. Besides, the largescale ecological engineering construction is the main driving factor for the increase of vegetation cover in the study area.

Key words：vegetation cover change; MODISNDVI; climate change; human activity; Panzhihua City