Abstract: Adopting subregional water supply in unevenly irrigated areas can raise water supply energy utilization efficiency. The largest economic results through optimized subregional water supply scheme can be obtained under the condition of the same investment and cost. This article further analyzes the total energy composition and the method to raise the energy use efficiency for water supply on the basis of research of predecessors. The optimization object function model based on the improved real coded accelerating genetic algorithm(RAGA) was developed to determine the optimal subregional scheme of the water supply system. The improved RAGA has some advantages such as accuracy and rapidity of calculation, good general-purpose usage. Therefore, it can be used extensively in optimization of subregional water supply in large irrigated areas.