Based on the 30 year data from 1981 to 2010 of the US National Centers for Environmental Prediction (NCEP),the process of seasonal temperature changes in Qinghai-Tibet plateau and its surrounding areas as well as the possible intrinsic mechanism are studied.The results show that the 24℃-isotherm of earth surface exhibits a sudden jump between the north and south about 18latitudes in February-March and November,which is speculated to be the result of the joint effects of the solar radiation and the monsoon circulation.The seasonal temperature change on 200 hPa is earlier than on surface and 500 hPa,presumably due to the downward energy transfer from the sudden warming stratosphere.The surface temperature in Qinghai-Tibet plateau is closely related to lesser downward longwave radiation flux.The results will provide useful hints for further research on climate change in Qinghai-Tibet Plateau.