The unsteady flow of the low specific speed centrifugal pump with curvature blade was simulated numerically by software Fluent, RNG k-ε turbulence model and sliding mesh technology. Three indicator points near tongue with impeller and volute were monitored and pressure fluctuation of those points was gotten. Then, the calculating values were compared with test values. The results show that splitter blades restrain the flow separation. The performance of the pump, the pressure distributions of the pump and jet-wake region are improved deeply. The pressure pulsation amplitude of the indicator points near the tongue is proportional to the distance between the volute tongue and points.