Abstract: Based on meteorological observations such as pan evaporation，temperature，sunshine hours，and wind speed，humidity during 1954-2013 in Xilinhaote station of typical grassland of Inner Mongolia，the annual and seasonal variation of evaporation was analyzed by using the linear trend，correlation analysis methods and complete correlation coefficient.The variation characteristics of the pan evaporation and the relations among pan evaporation and some meteorological factors were analyzed，and it attempted to explain climatic cause of evaporation changes.The results showed that the evaporation presented an obvious upward trend （51.49mm/10y，P＜0.01）in recent 60 years in Xilinhaote station of typical grassland of Inner Mongolia，especially in spring，summer and autumn.Analysis on the complete coefficients of meteorological factors with pan evaporation showed that mean temperature，minimum temperature and relative humidity were the main influencing factors resulted in pan evaporation increase （P＜0.01）.There was obviously positive correlation between evaporation and temperature，but negative correlation between evaporation and relative humidity，which indicated that temperature and relative humidity were main factors resulted in evaporation increase in Xilinhaote station of typical grassland of Inner Mongolia.The results could provide reference to climate change evaluation and analyzing in typical steppe region.

Key words: Typical grassland, Pan evaporation, Variation feature, Meteorological factor