The flow field of a centrifugal pump with the specific speed of 60 was computed by CFD method, and the analysis was made to the characteristics of energy conversion within impeller from aspects of working process and energy loss process. The impeller was divided into 8 regions by the radius. Under different operating conditions, characteristics in each region were demonstrated the power of pressure and viscous force, distribution of power density and turbulence dissipation rate, composition and distribution of the energy loss. The results indicated that efficiency was poor and it was influenced by the inlet blade angle in inlet region of the impeller, the middle region of impeller was important to the energy conversion, the outlet region of impeller had appreciable impact on the performance, and fiction loss was the main component of the energy loss.