Aiming at the problem that the large pressure step distance of hard thick roof in weakly consolidated area in western China was easy to cause severe ore pressure, the treatment scheme of water injection softening hard thick roof was put forward, so that the roof caving step distance was greatly shortened and the ore pressure appears significantly reduced. With No.113100 Face as the background, Flac3D software was used to simulate the field construction process, and the evolution of stress field and plastic zone in the stoping process of working face with or without water injection softening hole was compared and analyzed, and the optimal step distance of hydraulic softening roof was obtained. The construction scheme of drilling water injection to soften the roof was applied to the mining of No.113100 Face, so that the first pressing step of the direct roof was controlled at about 20m, and the first pressing step of the old roof was controlled at about 30m.The results showed that the initial caving step of the roof can be effectively controlled by water injection to soften the overlying roof in advance, so as to realize the purpose of caving in the predetermined position of the roof, minimize the instantaneous dynamic effect of the roof of the working face and ensure the safe mining of the working face.