Abstract: By using the data set with snow in 61 weather stations at east of Qinghai-Tibetan Plateau for the period from 1967 to 2010 and these methods of polynomial fitting,linear trend fitting,running t-test,correlation analysis,multiple regression analysis,we analyzed the interdecadal variations of snow cover and their relations with air temperature and snowfall over east of Qinghai-Tibetan Plateau. The result shows snow cover in winter and spring at east of Qinghai-Tibetan Plateau have the obvious characteristics of interdecadal change,little before the middle stages of the 1980 s,rich from the later stages of the 1980s to the later stages of the 1990 s,little again after the end of 20 th century. Snow cover in autumn at east of Qinghai-Tibetan Plateau show weak reduction linear trend. The shift of snow cover changing from less to more around 1987 only happened in winter. The shift of snow cover changing from more to less around 1997 significantly happened in winter and spring.The variations of snowfall and air temperature are the important factors on snow cover at east of Qinghai-Tibetan Plateau. The influence of snowfall is more important,especially in autumn. In the period of rich snowfall in winter or spring,the variations of snowfall dominates the variations of snow cover. In the period of poor snowfall in winter or spring,the effect of air temperature increase obviously,sometime it will be more powerful than snowfall,even to the extent of dominating the variations of snow cover at east of Qinghai-Tibetan Plateau.