The tropical cyclogenesis features over the Northwestern Pacific simulated by Regional Climate Model Version 3.1 (RegCM3) with 15 km, 30 km, 45 km and 60 km resolutions are compared. It is found that the capability of RegCM3 on tropical cyclogenesis simulation over the Northwestern Pacific is influenced by resolution. The increase of resolution cannot always lead to the improvement of the simulation result. RegCM3 with 30 km resolution has the best capability of simulation on tropical cyclone (TC) genesis number and its variation. The capability of simulation by RegCM3 with 45 km resolution on TC genesis number and its variation is a little worse than RegCM3 with 30 km resolution. RegCM3 with 60 km resolution has the best capability of simulation on TC genesis position. RegCM3 with 15 km resolution has the worst capability of simulation on TC genesis number, TC genesis position and the variation of TC genesis number. The processes of TC genesis simulated by RegCM3 with different resolutions are compared. The results are as follows: The vortices cannot merger because of the small scale of them and the far distance between them. It may result in the decrease of TC genesis number in the simulation of RegCM3 with 15 km resolution. Much dry air involves in wet air before TC genesis and then reduces the water vapor and condensation latent heat release in the mid and lower troposphere. It may also result in the reduction of TC genesis number in the simulation of RegCM3 with 15 km resolution.