The disc friction loss and axial force calculation of centrifugal pump and flow characteristics of balance cavity liquid are closely related. At operating points of 0.8Qsp, Qsp and 1.2Qsp, numerical calculation results and experimental results were basically consistent on performance of pump and flow characteristics of balance cavity. Distribution of velocity field was researched in the balance cavity. The distribution curve of dimensionless circumferential velocity component and dimensionless radial velocity component were drawn along the axial direction at different angles and radiuses of balance cavity to analyze the flow characteristics and calculate the disc friction loss in the balance cavity area. The results showed that flow core and turbulent boundary layer existed in the balance cavity liquid. The main flow characteristics were circumferential shear flow and radial differential pressure flow. The dimensionless circumferential velocity component of flow core decreased with the increase of radius, the dimensionless radical velocity component was approximately zero, while turbulent boundary layer liquid was greatly influenced by leakage flow, which was asymmetric under the same flow condition. The radical leakage flow in the sealing back-ring and the axial leakage flow in the balance hole of the impeller played an important part in the flow of radical velocity component at the turbulence boundary layer and circumferential velocity component at the balance holes area. The rotational angular velocity of balance cavity liquid at the same angle and radius increased with the increase of flow. The disk friction loss in the balance cavity decreased with the increase of the flow. Theoretical formula of disc friction loss did not consider the effect of variable flow conditions on pump. The theoretical results were greater than the experimental results and the numerical calculation results.