The improvement of numerical weather prediction depends on the improvement of the model physical process, the model initial field and model spatial resolution. The improvement of the model resolution has become an effective way to improve the model prediction effect. Based on the global forecast system, T1534 (13km) and T254 (55km) models with different resolutions were used to forecast the temperature, pressure, wind speed and precipitation over China. The results show that, among the two resolution models, North China has the best forecast effect. The correlation coefficients with ERA5 reanalysis data are all above 0.8, and the root-mean-square errors of the seven subregions decrease significantly with the increase of resolution. In the simulation of air temperature, the root-mean-square error in southwest China is 2.171, which is reduced by 30.1% to 1.523 after the model resolution is improved. In the simulation of wind speed, the correlation coefficients of the two resolution products are generally higher in the monsoon region than in the non-monsoon region. In a region with complex terrain, such as northwest China, the root-mean-square error of wind speed increases slightly with the increase of model resolution. It can be seen that the improvement of model resolution may not necessarily improve the accuracy of wind speed forecast. According to the heavy precipitation weather process in Shandong on August 10, 2019, the two models with different resolutions can simulate the precipitation characteristics well and cover the actual precipitation falling area. The deviation scores of various precipitation grades predicted by the high resolution model are lower than those of the low resolution model. In this heavy precipitation process, the relative humidity was close to saturation on the precipitation day, which was easy to condense, and with the improvement of the model resolution, the relative humidity was enhanced and the structure became more refined. Meanwhile, the central pressure of the low-level cyclone simulated by the high resolution model was lower than that of the low-resolution model, and the cyclone intensity was greater and the convective precipitation process was stronger.