Climate productive potential reflects the highest biological yield of vegetation community under natural environment,which can be used to evaluate grassland productivity. Based on data of 17 meteorological stations in Qilian Mountains from 1961 to 2013,this paper evaluated the productivity of grassland in summer (May to September) by using Thornthwaite Memorial model,Mann-Kendall mutation test as well as empirical orthogonal function (EOF) analysis method. The results showed that the tendency rate was 1.0552 mm·a~(-1) for precipitation, while 0.0357℃·a~(-1) for temperature. The climate change was warm and humid in Qilian Mountains,and the precipitation was the main impact factor for grassland productivity. With high value of first feature,the grassland productivity of Tuole-Yeniugou-Sunan area was significantly better than that of other regions,which should be regarded as the most important protected areas for the grasslands in Qilian Mountains. Under climate change the impact of precipitation on grassland productivity was much greater than that of temperature,especially in sandy area and the Gobi desert area,whereas the temperature was significantly affected grassland productivity in humid area, i. e. highland. This study provides reference for the protection and development of grasslands in Qilian Mountains.