Abstract: In this study, annual, spring, summer, autumn and winter average air temperature change sub-regions have been get by the REOF. The air temperature trends have been examined for those sub-regions. It is noted that eight, seven, nine, seven, and five sub-rigions can be taken for annual, spring, summer, autumn and winter respectively. The increase of annual average air temperature is mainly in the Northeast, the north of North China and Xinjiang, and it is about 1.2℃. The areas with negative trend of 0.3～0.4℃ are mainly in Sichuan and Guizhou provinces. In Southeast, east of Northwest, Xizang and Yunnan, temperature increase started from the 1970's after a decrease, the trend is similar with that of North Hemisphere. The seasonal temperature variation is different from annual. It is winter in which both the largest area and the maximum value of increase temperature was experienced. The decrease of temperature experienced in West and Sorth China in spring and in Changjiang Valley and the south of Xinjiang. The maximum decrease temperature experiencd in summer. There is not negative trend in autumn and winter.