This paper is to discuss some mathematical models to describe the particle acceleration in jet milling as we take the overheated stream and the air as the working medium, respectively. Furthermore, the corresponding numerical simulations are also investigated. Under the assumption of considering the heat transfer and without heat transfer, respectively, we discretize the particle motion equation and solve it by Newton iteration. These results show the trend of the velocity of a single particle in different density and different particle diameter sizes, respectively. Our results are benefit to the optimization of parameters design and system configuration in jet milling equipment.