Background: In the Northern Sahara unfortunately no plant domesticated by man can vegetate without a supply of water.The goal of irrigation is to maintain a moist bulb around the roots of the crop. The use of modeling is one of the most recent and effective means for determining irrigation regimes. Objective: AquaCrop and Cropwat are FAO models used to calculate water balances, as well as estimate crop water needs and evaluate yields. Given that they present differences in the calculation methodology Methods: we opted in this work to compare the water needs provided by these two models for sunflower, wheat, cotton and esparto in Ouargla and Touggourt. The Climwat model is used to obtain climate data. Results: The results obtained from evapotranspiration and water requirements provided by cropwat are higher than those of aquacrop for sunflower and wheat, and lower for Alfafa and cotton. The evapotranspiration of the sunflower in Touggourt provided by the cropwat is 563.3 mm and that of the AquaCrop is 494.9 mm and in Ouargla respectively, 611.4 mm and 575.6 mm.For Alfafa in Touggourt 1251.6 mm / 1506.7 mm and in Ouargla 1267.5 mm / 1606 mm. For cotton in Ouargla 1040.6 mm / 926.2 mm and in Touggourt 968.5 mm / 852.4 mm.For wheat in Touggourt 881.4 mm / 989.2 mm and in Ouargla 963.6 mm / 1089.8 mm. The results obtained for effective rainfall provided by cropwat are superior to those of aquacrop. Conclusion: In Ouargla those of cropwat are around 37.1 mm and those of Aquacrop 36.1 mm. Conversely for Touggourt 74.3 mm and 72.7 mm.