Using SWAP (soil-water-atmosphere-plant) model and dual crop coefficient approach presented in the FAO irrigation and drainage paper 56 (FAO-56, 1998, crop evapotranspiration, guidelines for computing crop water requirement), the evapotranspiration of the natural vegetation in Otindag Sandy Area was calculated. The main results indicate that SWAP model and dual crop coefficient approach can be used to simulate evapotranspiration. SWAP model can simulate soil profile soil volumetric moisture. 