Xinjiang grassland resources are rich and varied, but as far as current research is concerned, topography has not been fully considered as one of the most important environmental factors affecting vegetation productivity. This study takes Landsat and DEM as data sources, and the object of study is a grassland in Changji Prefecture of the Xinjiang autonomous region. The annual net primary productivity is calculated with the CASA model. The ArcGIS spatial analysis method is used to analyze the distribution of the net primary productivity in Changji Prefecture for the years 2000-2016. The results show that topography plays an important role in the distribution of productivity. The analysis of the influence of elevation, slope, and aspect show that slope is the largest impact factor, followed by aspect, and elevation is the smallest. In the overall characteristics, when the elevation increases by 30 m, the productivity increases by 4.11 g/m². In the same way, when the slope increases by 1 degree, the productivity increases by -0.225 g/m². The productivity of the north aspect is the highest (23.23 g/m²), and that of the southeast aspect is the lowest (3.54 g/m²). In years with different productivities, the trend of impacts is the same, but the ranges of variation are different. The three topographic factors have the largest range of change in high-productivity years.