Based on ANSYS FLUENT,the centrifugal pump of type DG-350 was selected as a test model.The N-S equations, the standard κ-εturbulent model and the simple algorithm were adopted in the simulation.The effects of different size of clearance of wearrings,which were 0.3,0.5,0.7 mm,on the pump properties were studied.Under different working conditions, the distributions of pressure, velocity and turbulent kinetic energy of the key parts such as the impeller, guide vane and wearrings clearance were obtained. The analysis shows that the clearance of the wearrings reduces the pressure difference between the inlet and outlet of the impeller; with the increase of the wearrings clearance,the energy loss, hydraulic loss and volume loss increase in the centrifugal pump, which decreases the efficiency of the centrifugal pump.