In order to solve the problem that aluminum coating on bolt surface may be uneven in thickness when aluminum paint was used to coat the bolts, the influence of spraying angle on the uniformity of bolt surface coating is researched in this thesis. Nozzles and bolts of the spraying system were modeled and the computational fluid dynamics simulation software Fluent was used to establish the physical model of the gas-liquid two-phase flow of the atomization flow field. DPM model was used to analyze the interaction between the gas phase and the liquid phase in the flow field. Besides, the spray flow fields at different angles were obtained. The thickness of liquid film deposition on the bolt surface was also predicted and the spraying test system was set up. Results of this research were verified with the simulation results. The simulation and experimental results all show that the bolt surface coating is the most uniform when the spraying angle is 30°.