Abstract: The temperature in Inner Mongolia,China keeps increasing from 1971 to 2016.According to the result of MK mutation test,there was a sudden change of the annual average temperature in 1988.The temporal and spatial variation characteristics about the dry and wet environment of the main vegetation types in the region was derived based on the analysis of the change and the tendency rate of the precipitation,potential evapotranspiration and moisture index before and after the sudden change of the air temperature in the course of the late 46 years.The results showed that the precipitation had the pattern of an increasing trend in the east area but a decreasing trend in the west area before the sudden change of the temperature,and it turned to an opposite pattern after the sudden change of the temperature which meant a decrease trend in the east area but an increase trend in the west area.The areas with a precipitation trend rate in the past 46 years were mainly concentrated in the east of Hulun Buir League and most area of the western Ulanqab League.The evapotranspiration showed a decreasing trend before the sudden change of the temperature,but an increase trend after that change,and the latent evapotranspiration was significantly smaller after the sudden change of the temperature.The potential evaporation tendency was relatively small in most areas in the past 46 years with the exception only in the northcentral part of Inner Mongolia.There was an obvious “evaporation paradox” in most parts of the region.The desert,steppe desert and desert steppe in the west region of Inner Mongolia were in the humid climate background,which was beneficial to the local vegetation construction and ecological recover.In southeastern Inner Mongolia,and the grasslands of Hulun Buir and Xilingol League there was a warming and drying tendency,which poses a potential degradation risk in the above steppe areas.It is required to strengthen the maintenance of natural fending and ecological stability of the grassland areas,to reduce human disturbance,and largescale artificial vegetation construction should be prohibited at present.The conclusion can provide scientific basis for regional ecological construction,vegetation protection,reasonable utilization of regional climate resources and climate change solutions.

Key words: Inner Mongolia, climatic change, precipitation, potential evaporation, dry and humid change