Due to climate change and changes in plant water needs, it is necessary to evaluate climate change in the coming decades with the aim of appropriate environmental planning to adapt to future climate conditions. The main factor of water resource consumption in arid and semi-arid regions is agriculture and consequently evapotranspiration, so knowledge of the change and its prediction plays an effective role in the planning, development, and management of water resources. The present study uses the Lars WG Model. Using this model, the temperature in three time periods (2011-2030, 2046-65, and 2081-2100) with four general atmospheric circulation models (IPCM, INCM3, HADCM3, and NCCCSM) in three different scenarios (world with sustainable development, rich world, and the isolated world) has been calculated, then the evapotranspiration changes were examined in the Southeast of the country in the three mentioned periods for eight stations. For this purpose, the Thornthwaite equation was used to calculate evapotranspiration. The results show an increasing trend of temperature followed by an increase in evapotranspiration in the coming period. The average increase in evapotranspiration in the NB1 model is less than other models and has the lowest value and the highest value in Kerman and Iranshahr, respectively. The relative changes of evapotranspiration until 2099 in Kerman and Iranshahr stations are 10.692 (mm / day) and 23.194 (mm / day), respectively