Abstract: This paper briefly discusses the difference of temperatures between the western and eastern parts south of the Kunlun-Qinling mountains of China.Comparison between the measured temperatures at weather stations and the temperatures obtained by conversion of the measured temperatures at sea level shows that the sea-level temperatures in the western,middle and eastern geomorphologic steps of China decrease gradually at 0.5℃/100 m from west to east.The annual average arithmetic temperatures in the plateau region of western China are higher than those in low,level region of eastern China,mainly because the climate of the Qinghai-Tibet Plateau of western China and the Southern Asian subcontinent has been controlled by the southwestern monsoons,while the climate in eastern China has been mainly influenced by the southeastern Asian monsoons and winter monsoons from high latitudes.Therefore,the global change and regional-scale monsoon climate are the primary cause responsible for the difference of arithmetic temperatures between eastern and western China,so we cannot broadly ascribe the temperature difference to the warming effect of the plateau and the effect of "cold troughs" in the east.