The steady and unsteady interflow fields in centrifugal pump with double curvature blade were investigated by CFD, which was compared with general centrifugal pump in the same design parameters. The characteristic of interflow fields and pressure fluctuations at different monitoring points were obtained. The results showed that it can prevent the impeller from emerging and developing wake flow in double curvature blade centrifugal pump. The main factor which created the pressure fluctuation in the pump was the interaction between the impeller and the tongue, and with the flow rate increased, the pressure fluctuations at the tongue were getting bigger. At the same flow rate, the pressure fluctuation’s amplitude value on double curvature blade type centrifugal pump was smaller than the ordinary centrifugal pump, which reduced the pump’s hydraulic loss to some extent. The results are served as the theory basis in optimization of pump structure and reduction of pump’s noise and vibration.