The turbulent flow field of jet pump is simulated with model in different nozzle inlet velocity. Distribution of velocity, pressure, turbulent kinetic energy are got. Analysis of flow field characteristics shows that turbulent kinetic energy peaks are generated at the nozzle outlet and the beginning of diffusion tube, dimensionless turbulent kinetic energy peaks are at different radial locations for nozzle outlet but they are the same at the beginning of the diffusion tube. Analysis results of external characteristic show that the simulation results of turbulent flow agree well with the theoretical value. Finally, impact factors of the jet pump efficiency are analysed, finding out that the main factors is the loss of fluid mixing in the context of low flow ratio, and the main factors in high flow context is friction losses of throat and diffuser pipes. The results of this study are instructive for further numerical simulation and application of engineering.