Abstract: The study area is one of the important agricultural areas in the Mekong Delta of Vietnam. It has an important contribution in term of food security and economic development in Vietnam. In recent years, this area has seriously impacted by salinization, drought due to the impact of climate change leading to the irrigation water scarce for agricultural production. Therefore, the accurate estimation of irrigation water requirements is very necessary and especially in the context of the climate variability. The aim of this study was to define irrigation water requirement, net irrigation requirements and to conduct efficient irrigation schedule for improved irrigation practices order to provide information necessary in taking decisions on irrigation management under the impacts of climate change. This study is conducted applying the CORPWAT crop model based on meteorological factors recorded from 2004-2015. The simulated results showed that the crop water demand of the Winter-Spring, Summer-Autumn and crop water demand cropsvarying from 0.0-176.8 mm/dec. The high crop water demand was recorded in the Winter-Spring, Summer-Autumn crops (from 593.4-827.8 mm) and lower was observed in the Autumn-Winter crop (236.3 mm). The highest Crop Water Demand (CWD) values of Winter-Spring, Summer-Autumn crop was occurred from the mid-second decade to the end of the third decade and the lowest CWD value was close to zero on the four decades to the mid-sixth decade of the Autumn-Winter crop.The simulation results showed that CORPWAT crop model can be successfully applied to define reference Evapotranspiration (ET ), actual Evapotranspiration (ET ), Effective Rainfall (ER), CWD and irrigation o C conditions with reasonable accuracy.