Abstract: For the study on complete characteristics of LOCA reactor coolant pump, three-dimensional modeling for the pump internal flow channel by pro/E, based on the Reynolds-averaged Navier-Stokes equations with the RNG k-ε turbulence model and SIMPLEC algorithm, using the computational fluid dynamics software CFX to conducts the numerical simulation calculation for complete characteristics of reactor coolant pump, complete characteristic curves have been analyzed, and reasons of the hump phenomenon in small flow conditions are explained. The result shows that: numerical simulation method is feasible to calculate complete characteristics of reactor coolant pump. The impeller torque is mainly from the blade, and the torque of the front and rear shroud has little effect on the impeller torque. The torque and axial force of blade have similarity trend with Q-H curve, and they are closely related.