Simulation of the velocity field of solid-liquid flow inside and outside the abrasive water jet nozzle was studied by the computational fluid dynamics software(CFD). The velocity field of the flow in the abrasive water jet (AWJ) nozzle was obtained. The results indicate that the swirl is produced in the nozzle and the abrasives are all distributed along the inner surface of the nozzle. The velocity at the center of the outlet face is the highest, while it is smallest at the both edge. The dispersion of the flow is happened when it flows out of the nozzle, but the flow velocity away from the outlet at a distance of about 4 times of the outlet diameter changes little. The fillet diameter, the inner cone angle, the length of mixing tube of the nozzle greatly affect the field of two-phase flow. The velocity of outlet increases with an increase in the fillet diameter, the flow becomes ease when the cone angle decreases, the mixing tube hampers the two-phase flowing.