How to accurately estimate the actual evapotranspiration in arid areas is a heated and difficult research topic. In order to explore a suitable method for calculating regional evapotranspiration in Xinjiang, the MOD-16A2 and AET data sets were used to verify Fisher′s model (PT-Fi model) based on Priestley-Taylor and plant physiology theory. The actual evapotranspiration and its components of whole Xinjiang, southern and northern Xinjiang during 2001-2010 were calculated using this model. The results showed that the PT-Fi model performed well in the simulation of actual evapotranspiration of the studied areas. The annual average proportion of soil evaporation was 69.3%, that of vegetation transpiration was 29.64%, and the rest was canopy interception evaporation. The evapotranspiration ratio of southern Xinjiang was about 1∶3, and that of northern Xinjiang was about 1∶2.