The paper used Penman-Monteith equation and Priestley-Taylor equation to calculate the reference evapotranspiration of Duolun，and analyzed the change of ET0. Through contrast，ET0 value calculated by Priestley-Taylor equation is larger，but the trend calculated by two methods is almost the same．Using the results calculated by Penman-Monteith method as the standard，the paper analyzed the trend of ET0 change and features and correlation between ET0 and different elements．The research showed that yearly ET0 was far greater than annual rainfall in the area．The ET0 has a slight decrease trend on the whole，and presents a process of smooth - increase - decrease．Wind speed and sunshine have a larger impact on ET0．The results may provide some references for agricultural production and human activities．