Aiming to study the cavitation characteristics under different cavitation numbers based on the pump-turbine of a pumpedstorage power station, the SST k-ω turbulence model and the Zwart cavitation model were used to calculate the full flow path under different cavitation numbers. The unsteady numerical calculations were carried out and compared with the experimental results. The turbulent kinetic energy distribution of the intermediate flow surface and the distribution of cavitation on the blades under different cavitation numbers were analyzed. The correlation between cavitation distribution area and the runner inner channel vortices were discussed. The results showed that when the pump-turbine was operated under pump conditions, its vaneless had obvious turbulent kinetic energy, and the turbulent energy distribution was obvious, showing an irregular ring shape distributed. The bubble distribution of the blade was mainly on the suction surface of the blade, and the turbulent energy of the suction surface of the blade was higher than that of the pressure surface. The vortex inside the runner was mainly generated near the exit of the runner, and close to the suction surface of the blade. The size and number of vortices had a certain relationship with the distribution of bubble on the blades. The generation of bubble led to the poor flow path and exacerbated the generation of vortices. 