The wall wettability of chip microchannels in droplet microfluidic is one of the important factors that determine droplet generation. In order to study the influence of surface wettability of cycloolefin copolymer (COC) microchannels on droplet formation and fluid flow behavior, VOF model was used to simulate the flow behavior of water and fluorine oil in focused flow microchannels, and the microchannels with contact angles of 30°, 90°and 120°were prepared for experimental study. The simulation results were in good agreement with the experimental results. The results show that under the fixed physical and structural parameters, the weaker the wettability of the wall is, the easier it is to form water-in-oil droplets, and the drag reduction characteristics of the wall will be enhanced. Moreover, the drag reduction characteristics of the wall will result in the droplet generation frequency being 29.3% lower and the diameter increasing by 8.3% at 90°than at 120°. With the increase of wettability, the interface between water phase and fluorine oil phase changes from convex to concave, and the droplets generated by chip change from water-in-oil to oil-in-water at 30°; With the increase of capillary number of continuous phase, the influence of wall wettability on droplet formation decreases.