Abstract:The origins,purpose,features and polishing principle of abrasive water jet were introduced,aiming at defects of polishing surface quality and service life of the abrasive sand tube when the abrasive particles in the mixing cavity mix unevenly with high pressure water,through studying on the cutting nozzle structure of abrasive water jet,symmetric double feeding nozzle geometry model was established and simulation research on the internal flow field in the nozzle was carried out using the CFD software,menwhile,the influence of mixing homogeneous degree between nozzle contraction cone angle on the abrasive particles and high pressure water beam was analyzed.The results show that selecting 30°and 45°contraction cone angle is beneficial to extend the service life of sand tube and make abrasive particles mix evenly with water jet,accordingly,advance the surface quality of the workpiece in finishing.