Regulated deficit irrigation is through active exerting a certain degree of water stress artificially, exercising the crop drought resistance, affecting their physiological and biochemical process, in order to achieve the goal of saving water and increasing production. Taking maize as research object, the experiment was carried out in micro test pit area, and the influences on soil water distribution, root length, root length, root number, yield and crop water utilization efficiency were studied under drip irrigation on ground. Five different treatments (C1,C2,C3,C4 and C5) were set, which were slight and moderate regulated deficit in seeding and jointing stage, separately, and moderate regulated deficit in seeding stage while slight regulated deficit in jointing stage in 2016, and the whole growth period with suitable irrigation (CK) was set as control treatment. The result showed that the final water content of filtration cake in the crown of the maize was increased by -6.03% ~ 4.61% and 1.30%～8.15% in the root. At the same time, the yield of C1, C4 and C5 was decreased by 7.89%, 23.47% and 28.13%, respectively, while that of C2 and C3 was increased by 5.20% and 1.49%, respectively, water use efficiency was improved by 0.33%, 26.25%, 18.27%, 6.64% and 16.94%, respectively, and five treatments saved 8.26%,16.71%,14.07%,28.35% and 38.54% of water, respectively. The moderate treatment in seeding stage and the mild treatment in jointing stage were the appropriate water deficit treatments for maize under drip irrigation in water saving and production increasing. The result was of practical significance to guide the establishment of reasonable irrigation system for maize in western area of Heilongjiang Province.