Abstract: The differences between the crop canopy temperature and the aii temperature for both Tibetan plateau and eastern part of China are investigated. By comparative study it is found that there exists the property of the same value of accumulated temperature but with different effects for crop-growing in the Tibitan plateau and eastern part of China. The upper limits for many crops are much higher on the plateau than in the eastern part of China. Some suggestion referring to raising the yield of crop on the plateau are presented.