It is important for precise fabrication to research the material removal model of polishing. Simulation is done by computational fluid dynamics for fluid jet polishing (FJP). Numerical research and theoretical description for abrasive particles discrete system are taken by population balance modeling method, and experiments are taken to research the removal profile by vertical fluid jet polishing (VFJP). The results of experiment and simulation show that the removal profile of VFJP turns on a W-shaped profile. By analyzing the material removal mechanism of FJP that material is removed by particles impinging wear and wall movement erosion, the mathematical material removal model of VFJP is enduced. Comparing the mathematical material removal model with the experimental removal profile, it is found that the mathematical material removal model of VFJP is accurate.