Abstract: The treatment of cutting the spring wheat roots in pot experiment shows that injuring the spring wheat rootsn1oderately in early time can boost the photosynthetic rate and promote the accumulation of the photosynthetic production，improve the water use efficiency(WUE)of spring wheat leaves，and finally increase the grain yield．However，injuring the spring wheat roots in the time of stem elonging mostly restrains the growth of the spring wheat，and the yield is decreased．