Trees at alpine timberline are highly sensitive to environmental changes. However，how climate changes alter the spatial and temporal dynamics of tree growth at alpine timberline remains unclear. We have collected 480 tree cores from 10 sample points of alpine timberlines at elevations of 3210-3426 meter to study the growth dynamics of Qinghai spruce on different precipitation gradients. The results show that there is a significant difference in the response of tree growth to climate changes between the areas to the east and west of Sunan County in the Qilian Mountain. The growth of Qinghai spruce to the east of Sunan County in the Qilian Mountain is mainly subject to temperature，while that to the west is mainly subject to precipitation，mainly due to the changes of moisture gradient in the east-west direction of the Qilian Mountain. The climate warming has contributed to a significant upward trend in the growth of Qinghai spruce to the east of Sunan County in the Qilian Mountain，while the growth of trees to the west of Sunan County fluctuates smoothly. The results show that future climate warming may promote the growth of Qinghai spruce to the east of Sunan County，being relatively humid，while the growth trend of Qinghai spruce to the west of Sunan County，being relatively arid，is more complex and depends mainly on the degree of drought caused by temperature and precipitation. This research has provided a theoretical basis for forest ecosystem management and conservation in the Qilian Mountain under the background of climate changes.