Abstract: In order to study the effect of the different entrance sections of hydraulic turbine on pressure fluctuation within volute, a single stage hydraulic turbine was selected, and internal flow field of hydraulic turbine was calculated by using software CFD. We set monitoring points along the circumference and radial direction of volute and calculated the pressure fluctuation along the circumference and radial direction at each monitoring points under the different entrance sections and the optimum conditions of hydraulic turbine. Pressure fluctuation were also calculated along the radial direction at each monitoring points under the different entrance sections and the different flow rates, and the results of numerical calculation were dealt with at each monitoring points by using FFT. We analyzed the distribution rule of time domain and frequency domain of pressure fluctuation at each monitoring points. The results show that the greater the inlet diameter of volute is, the greater the pressure pulsation would appear at the tongue. The smaller the inlet diameter of volute is, the greater the intensity of dynamic and static coupling between the impeller and the volute would present. These lead to bigger amplitude of pressure fluctuation in the volute. With the increase of flow rate, the difference value of amplitude of dominant frequency gradually decreases in the volute under the different volute import. When the centrifugal pump is used to hydraulic turbine, in order to make hydraulic turbine to steady work, the area of entrance section of hydraulic turbine should be appropriately reduced.