Qilian Mountains is an important ecological barrier in China. Quantitative assessment of the effects of climate change and human activities on vegetation variation is of great significance to the ecological protection and restoration of the Qilian Mountains. The temporal and spatial dynamics of vegetation coverage in the Qilian Mountains from 1986 to 2020 were analyzed. The contribution rates of climate change and human activities to vegetation coverage variation were calculated. Furthermore, the influences of ecological restoration project on the change of vegetation coverage were evaluated. In this paper, using the Google Earth Engine platform of Landsat NDVI, Qilian Mountains ecological restoration through JavaScript programming code research before and after the change of vegetation coverage. At the same time, in order to quantitative evaluate the contribution of climate change and human activities, by adopting the method of multiple regression residuals in Qilian Mountains before and after the ecological restoration of vegetation coverage change were analyzed. And then explore the role of ecological restoration engineering in Qilian Mountains, and which will provide a scientific basis for later of Qilian mountains ecological restoration plan and the development direction. The results showed that:(1) the vegetation coverage in the Qilian Mountains showed a significant increase trend with the increase rate of 0.022/10a from 1986 to 2020. There was a transition from the middle-low coverage to the middle-high coverage after the project of returning farmland to forest and grassland in 1999. (2) Vegetation variation in the Qilian Mountains is the result of climate factors and human activities. The contribution rate of climate factors to vegetation coverage is 93.40%, and that of human activities is 6.60%. Qilian Mountains region of vegetation coverage change and the precipitation, air temperature, drought index expression is significantly positively related, and the relative humidity is negative correlation. During the study period, drought index, the temperature had the greatest influence on vegetation growth, in other words, vegetation coverage affected by the local drought degree is the largest, the average temperature on the influence degree of the vegetation coverage shows the trend to increase, and drought index, the precipitation is characterized by weakening trend. Climate is the dominant factor of vegetation variation in Qilian Mountains, but the influence of human activities is increasing year by year. Ecological projects are the main driving force of vegetation coverage improvement in the Qilian Mountains such as returning farmland to forests and grassland, which also laid a good foundation for the follow-up vegetation restoration and ecosystem stabilization.