Abstract: For the anti-icing problem of the engine air induction part with low thermal conductivity composite material, the combined heat transfer method using impingement and jet air film has promising application, while there is still a lack of systematic studies of the effects of jet air film on the water droplets impingement. The numerical simulation algorithm of three dimensional water droplet impingement based on Eulerian- Eulerian method was developed and verified by experimental data from references, where the convergence of algorithm was improved with the diffusion coefficient. The droplets impingement characteristics of the three dimensional cylinder with two parallel jet holes under three different blowing ratios (0.5, 1.0, and 1.5) were then studied. It is found that, the strong coupling between the jet air film and the main stream leads to different mechanisms of blowing off and diffusion between the jet air film and water droplets, which are closely related to the jet intensity and position. For typical droplet diameters (20 μm) with certain velocity (30 m/s), the trajectory and vorticity field of water droplets at six spanwise cross-sections and one center section cross the holes were analyzed. At small blowing ratios (0.5 and 1.0), the jet air film effect is limited to spanwise near-hole cross-sections, and the impingement coefficient of water droplets between holes is reduced by a maximum of 7.51% compared with that without air film. When the blowing ratio is increased to 1.5, the effect of jet blowing off and diffusion is stronger, and the water droplets between holes are blown outward along the extension direction, resulting in the decrease of the water droplets in the near hole section and the increase of that in the far hole section. The water droplets impingement coefficient of the cross-section between holes is reduced by a maximum of 8.95% compared with that without air film, and the water droplets impingement coefficient is reduced by a maximum of 17.65% from extending outward to between holes. In this paper, the effects and its inner mechanisms of hot jet film on the droplet impingement characteristics were analyzed, which provides a reference for the design of the hot air film anti-icing system.