Abstract: The paper optimizes the structure and parameters of nozzle at jet mill device with software and theories of engineering thermodynamics examining the performance of the designed nozzle by simulating its flow fields with liquid simulated software as well as discussing the effection of passage shape and diffuse angle on supersonic nozzle. The optimized nozzle was then designed to be one with opening pressure of 3.5MPa and opening diameter of 6mm after comparing different simulations. When changing between 8°and 12°, the diffuse angle poses little effect on the performance of the designed supersonic nozzle. And when it is of curve shape, the passage shape betters the performance of the supersonic nozzle.