The basic equation of axial flow pump is derived from the assumption， which axial plane velocity and circumferential velocity distribute linearly along the blade radius. Based on the basic equation, the axial plane velocity and circumferential velocity gradient of discharge blade are calculated, and the flow field of pump is built. Using arc method of design blade, a design case is given. The standard K- epsilon turbulence model is applied to simulate the flow field of axial flow pump by FLUENT software. The simulation results indicate that pump efficiency reach 91%, there aren’t impact or vortex in pump, and the pressure distribution on the blade suction surface is even and high, the anti-cavitation performance is improved.