Abstract: Trend analysis was calculated by using normalized difference vegetation index（NDVI） and precipitation utilization （RUE） combined with least square method to determine the interference intensity of human activities on the vegetation changes in the source regions of rivers in Northwest Sichuan from 2000 to 2014. Research results showed that the vegetation intensity in the study area improved generally from 2000 to 2014. During 2000 to 2010, vegetation intensity in the study area recovered well. The significantly degraded areas of vegetation were significantly more than the significant recovery areas in study area from 2010 to 2014. In 2000—2014, the interference of anthropogenic factors on vegetation changes was dominated by negative interferences. The negative interference area accounted for 57.59% of the total area and the positive interference area accounted for 21.85%. Among them, human activities in the study area from 2000 to 2005 mainly showed a moderate positive disturbance on the vegetation changes, mainly mild positive disturbance from 2005 to 2010, and negative disturbance in 2010 to 2014 is serious. In the study area,negative interferences of human activities on vegetation changes are dominated by slight negative disturbance, mainly distributed in Shiqu,Aba, Hongyuan and Ruoergai counties. Man-made negative interference is mainly located in Shiqu county. Man-made positive interference is concentrated on man-made positive interference, mainly concentrated in the northern part of Shiqu county. No obvious human interference areas are mainly distributed in Ganzi, Seda, Rangtang counties.

Key words: NDVI, RUE, vegetation changes, trend analysis, human activities