Many regions in eastern pastoral areas of Inner Mongolia locate in far distance and have limited meteorological stations, the calculation of ET0 in application of FAO56 Penman-Monteith formula is relative difficult. In order to calculate ET0 accurately under the condition of lack of meteorological data ,the paper relied on data of typical meteorological stations,and took FAO56 Penman-Monteith as standard method,took methods of FAO17 Penman,Priestley-Taylor,Irmark-Allenfitting and Hargreaves-Samani as comparative method to compute ET0,and evaluated the applicability of the four methods.The results show that the values calculated by methods of Priestley-Taylor and Hargreaves-Samani are greater than that by FAO56 Penman-Monteith method,and are not suitable for the region.FAO17 Penman method and Irmark-Allen method got approximated calculation results whose relative error is less than 15% and had great accuracy. However, Irmark-Allen method need only meteorology data such as air temperature and sunshine time.Therefore,Irmark-Allen method is suitable for eastern pastoral areas of Inner Mongolia to calculate ET0 with lack of meteorological data.