Land use affects regional weather and climate. The use of land-use data that is updated and closer to the observation can provide strong support for numerical prediction. The high-temperature processes in August 2019 in Sichuan Basin are simulated by using the mesoscale numerical model WRF. Updated land-use datasets extracted from MODIS data are compared with original WRF datasets, and the influences of updated land-use data on WRF simulation are analyzed. The results show that there are significant differences between two sets of land use data, the updated data is more detailed, and the land use types of the simulated area are more abundant. The 2 m temperature is very sensitive to land use data, with update of land-use data, the accuracy ratio (absolute errors less than 2 ℃) of simulated 2 m temperature increased by 6.2%, and that of daily maximum temperature increased by 31.3%; the accuracy of simulated daily minimum temperature decreased by 2.1 %. Simulated temperature increases significantly in the Sichuan Basin where the land-use changed obviously, the increase in some areas is more than 4 ℃, and the negative bias in simulated daily maximum temperature by using original land-use datasets significantly reduces. The Hechuan station is selected as a typical station in the Sichuan Basin for analysis, where land-use type is changed from croplands to urban and built-up. It is found that after the change of land use type, the emissivity decreases, the roughness increases, and the stomata resistance of vegetation increases, and as a result, the upward sensible heat flux increases, surface evaporation and atmospheric water supply reduces, 2 m temperature increases, and planet boundary layer height increases. Updated land-use data results in strong locality of the simulation difference in the initial stage, as the lead time increases it gradually affects the upper atmosphere and surrounding areas. Land-use data lead to differences of simulations by affecting the selection of land-surface parameters. The accuracy of simulated 2 m temperature and maximum temperature are improved with update of land-use data.