Abstract: A high-resolution hydrodynamic numerical model based on the Regional Ocean Modelling System (ROMS) for the China Seas was built, with FIO-COM reanalysis data as boundary forcing. The model simulated tidal results agree well with the EOT20 satellite observations, suggesting that the tides in this region are predominantly influenced by tidal waves from the Pacific Ocean and split into a northern branch and a southern branche. Furthermore, the locations of tidal amphidromic points were simulated accurately. To evaluate the model performance in simulating sea surface temperature (SST) and sea surface salinity (SSS), statistical analysis methods including bias ( \mathrmb\mathrmi\mathrma\mathrms ), mean error ( \mathrmM\mathrmE ), mean absolute error ( \mathrmM\mathrmA\mathrmE ), root mean square error ( \mathrmR\mathrmM\mathrmS\mathrmE ), and correlation coefficients (R) were utilized. The results indicate that the seasonal variation of the modeled SST and SSS are close to the OI SST and SMAP SSS observational data. The spatial correlation coefficients between the simulated SST and OI SST observation data for all seasons exceed 0.989, while that of the annual mean SST and SSS can reach 0.997 and 0.95, respectively. Additionally, the model also successfully simulates the seasonal variation of the currents in the China Seas as well as the structure and lifecycle of the Yellow Sea cold water mass.