Qilianshan Mountains is one of the most important ecological function areas in northwest China and the water conservation area of Hexi oasis. Understanding the growth and variation of vegetation is helpful to formulate reasonable strategies of climate change. Using the date of GIMMS NDVI from 1982 to 1999 and MODIS NDVI from 2000 to 2014,the variations of vegetation in growing season and its response to climate change were studied in Qilianshan Mountains nearly 35 years by the maximum synthesis method, average method, slope method, correlation analysis method. The results showed that vegetation NDVI appeared an increasing trend in Qilianshan Mountains from 1982 to 2014, but it was not obvious. The area of increasing rate of vegetation NDVI was larger than its decreasing rate, which indicates that the vegetation cover of Qilianshan Mountains had been improved in the past 35 years. The regions of vegetation NDVI increase concentrated in the Midwest,but the decreased regions was in the eastern Qilianshan Mountains. The inter-annual change of climate has some influences on the vegetation NDVI in Qilianshan Mountains, and the vegetation NDVI has a certain lag response to temperature and precipitation. The increases of temperature and precipitation are helpful to the increase of vegetation coverage,so as to improve the ecological environment in the Qilianshan Mountains.