Abstract: Studies on the regulated irrigation of spring wheat indicate that in an arid environment, the soil water potentials of spring wheat are lower in the regulated deficit irrigation treatments than that in the no-water-deficit control from jointing to booting, and 14.3～66.5mm more stored soil water is consumed under the regulated deficit irrigation. Significant differences are observed in yield, kernels per spike, and water use efficiency of spring wheat under the regulated deficit irrigation as compared to the control. The yield, kernels per spike, and water use efficiency of wheat are greatly improved rather than inhibited by water deficit. The proper soil water deficits of spring wheat are water deficit(45%～50% of field capacity) at the vegetative stage(jointing)and free from water deficit at the other growing periods such as booting, heading, and filling to pre-physiological maturity(65%～70% of field capacity). Correspondingly, the optimum total irrigation water is 330mm to 350mm. In addition, the regression analysis presents quadratic relationships between seasonal evapotranspiration and yield, water use efficiency of spring wheat under the regulated deficit irrigation.