To decrease the flow unsteadiness in pump hydraulic design procedure as much as possible, the inner flow unsteadiness intensity and distribution should be understood. For analyzing the unsteady flow phenomenon in low-specific speed centrifugal pump, CFD software was employed to simulate the 3-D unsteady fluid flow in the pump, and meanwhile the time-averaged unsteadiness intensity coefficients were defined based on velocity triangle in order to directly depict the flow unsteadiness. By analyzing the distributions of the intensity coefficients in the low-specific speed pump, the results show that stronger flow unsteadiness can be found near blade suction side, and in the wake flow area the flow varies with time strongly. In addition, strong flow unsteadiness is also significant in the discharge tube and the area near impeller outlet of the volute.