Abstract: The growing shortage of water resources and increasing demand of agricultural water is a serious contradiction which we human have faced. It’s regulated deficit irrigation (RDI) that provides us an available way to solve the problem. The development and theory of RDI, the specific application of RDI in plant of muskmelon and the effects of RDI on yield, quality, WUE of muskmelon will be introduced in the paper. It demonstrate that not only the fruit quality could improve and the yield would remain stable even increase, but also the WUE will become more efficient, if suitable water stress is applied on muskmelon on a appropriate period. Lastly, some main problems and shortage in RDI up to now are pointed out and summarized, which make us a bold outlook, to help scientists break through continuously and gain new achievement.