The change of evapotranspiration is an important factor directly affected by climate change in the surface heat and water balance. In this study,we used the Penman - Monteith equation to calculate potential evapotranspiration, and utilized variety statistical methods to quantitatively analyze the evapotranspiration of Manas River basin of Xinjiang in the arid area during the past 60 years. The results show that the annual mean evapotranspiration of Manas River Basin was 1521. 43mm. The rate of evapotranspiration increase was 15. 8mm/10 years. In nearly 60 years,the diversification trends was " increase - decrease - increase - decrease" ,it was an abrupt point in 2005. The main cycle of evapotranspiration change was 18 years. Correlation analysis among precipitation,temperature,wind speed and evapotranspiration showed that the increase of evapotranspiration mainly was due to the increase of temperature; temperature and wind speed were the major factors affecting the potential evapotranspiration of Manas River Basin,precipitation minimally impacted on evapotranspiration.