Abstract: This study is focused on water use aspects with the aim of: calculating reference and actual evapo transpiration; determining Crop Water Requirement (CWR) and Crop Irrigation Requirement (CIR) and constructing Efficient Irrigation Schedule (EIS) for three main crops, including winter-spring, summer-autumn and autumn-winter using the Cropwat model based on monthly meteorological data recorded from 1984-2015. The results showed that winter-spring and summerautumn harvest needed irrigation water approximately 8186 and 5830 m³ ha^–1 while autumn-winter harvest needed approximately 2204 m³ ha^–1. The lowest value of the reference Evapotranspiration (ET_C) is approximately 607.8 mm crop occurred autumn-winter crop while the highest value 709.9 mm crop occurred summer-autumn crop. The highest IR of the winter-spring, summerautumn crops occurred on development stage with net irrigation approximately 499.5 and 397.1 mm, respectively. While the autumn-winter crop occurred on both growth, development and late stage with average net irrigation approximately 307 mm. The results obtained confirm that the Cropwat model with meteorological and soil data as input variables is successfully applied to define actual Evapotranspiration (ET_°), ET_C, CWR and EIS for three major crop seasons of rice in LXQ areas, vietnam with reasonable accuracy.