The climate change and its induced ecosystem change have gotten more and more attentions from scientists and societies.The past researches showed that the temperature and precipitation variations in southwestern mountainous area of China were different from those in the other parts of China.So the climate change and its impacts on ecosystem in southwestern China is still a question to be understood.In this study,the spatial distributions and interannual variations of net primary productivity(NPP)were simulated by the atmosphere-vegetation interaction model(AVIm²)in southwestern China.The responses of forests,shrub lands,grasslands and crop lands to temperature and precipitation change during 1980 to 2000 were discussed.The study indicates that the spatial distribution of vegetation NPP in southwestern China is positively correlated with the pattern of precipitation and negatively correlated with that of elevation.The total vegetation NPP of southwestern part increased in the 20 years period.More detailed analyses show that variation of plant function type's NPP are different due to precipitation in the areas where they are located varies.In forest area,where the mean temperature rise rate is 0.037℃ per year and the precipitation has no obvious trend,the simulated annual NPP does not show any increase or decrease trend.In shrub lands and grasslands area,where the temperature rise rate is 0.040℃ and 0.034℃ per year,individually,and the precipitations increased,both the simulated shrub and grass NPP show significant increase tendency.