Abstract: Under the condition of control test, by cultivating in pots containing soil,with maize as material, the Regulated Deficit Irrigation(RDI)was studied.The results showed that RDI in maize was a practicable technology for watersaving,highyield and highefficiency.Under appropriate amount of water deficit at right stages,the transpiration rate decreased obviously,and the photosynthesis rate diminution was not obvious. There were supercompensative effects in photosynthesis and photosynthetic products accumulation after rewatering. The proportion of photosynthetic products distributed in the grains tends to increase. RDI was able to control vegetative growth,increase rootshoot ratio,raise root obsorption activities and promote antidrought resistance of plant. The indexes of RDI for watersaving and highyield in summer maize as follows:the stages of regulated water deficit is threeleavesjointing, the amount of water deficit is 45%θ_ｆ～65%θ_ｆ,or regulated water deficit during jointingheading,the amount of water deficit is 60%θ_ｆ～65% θ_ｆ,and the water deficit duration is 21 days. RDI increased yield by 25.24%, water consumption decreased by 15.41%, Water use efficiency(WUE) increased by 45.05% as compared with conventional irrigation.