Abstract: For the shortcomings,such as low efficiency of jet energy and poor uniformity of water and abrasive in the post-mixed abrasive water jet descaling nozzle,three kinds of structures of the nozzle were put forward:the side feed nozzle,the tangential feed nozzle,and the parallel multi-jet nozzle. Based on the CFD Eulerian multiphase flow model,the 3-dimensional numerical simulation of the three kinds of structures was conducted with the FLUENT software. And the acting mechanism of the high-pressure water with the abrasive was analyzed through the velocity vector of the flow field inside the nozzle. The uniformity of the flow field was compared by analyzing the volume fraction contours of abrasive. Results show that compared with the side feed nozzle,the tangential feed nozzle and the parallel multi-jet nozzle can improve the mixing effect and obtain a rather uniform abrasive distribution. Whereas,the tangential feed nozzle can augment the internal wear of the nozzle,which needs a kind of more wear-resistant material. Compared with the former two structures,the mixing effect of the parallel multi-jet nozzle is perfect and the water jet flow as well as the acting mode could be adjusted according to the need in practical application.