The purpose of this paper is to study the three-dimensional unsteady numeral simulation of the whole flow passage in the reversible pump turbine. To this end, the geometric model was established by CFD numerical simulation method, and the rated flow of the three-dimensional whole flow passage of the pump turbine was simulated by SIMPLE algorithm. Then, the pressure pulsation of each part in the pump turbine was monitored. The study found that under small flow conditions such as 0.19Qr and 0.473Qr, with the load increasing, the opening of the movable guide vanes increased. Thus, it can be concluded that as the load increases, the opening of the movable guide vanes increases, the jet flow decreases, and the flow field in the vaneless zone tends to be flat and stable.