Aiming at the problem that the internal structure of the hydraulic valve block channel is complex and it is difficult to carry out precision machining,the abrasive flow precision polishing technology was proposed to realize the machining process,and the fluid simulation software Fluent was used for numerical simulation to explore the effects of import pressure,concentration of abrasive flow,particle size of abrasive particles and other factors on abrasive flow machining.The research object was the channel of hydraulic valve block,the simulation was carried out for the inner channels velocity,turbulent kinetic energy,static pressure and wall shear force under different import pressure,concentration of abrasive flow,particle size of abrasive particles.The conclusion is drawn:when the import pressure is 8 MPa,the volume fraction of abrasive flow is 0.1 and the particle size of abrasive particles is 200,the polishing result of the valve block channel is better.The corresponding abrasive flow machining experiments were carried out with these parameters.The results show that the surface roughness of the inner wall surface of the valve block channel is significantly reduced and the surface quality is improved.