In order to improve the level of Chengdu fine weather forecast, using Chengdu fine underlying surface data, the urban meteorological characteristics of Chengdu are simulated by the WRF coupled with singlelayer urban canopy model for a clear day, on July 6, 2008, and those are compared to simulations with old landuse data and slab model. The result shows that because of urban impervious underlying surface area increasing, the surface evaporation and upward moisture flux are significantly reduced, latent heat flux decreases and sensible heat flux increases. Urban buildings can intercept longwave radiation energy, so urban turbulence enhances and boundary layer height becomes higher; With the fine landuse data and singlelayer urban canopy model, both negative bias and rootmeansquare error of 2m temperature decrease; Urban area expansion and more buildings have led to the result that the urban heat island effect strengthens, urban 10m wind speed decreases, heat circulation between urban and suburban areas enhances, and local vertical circulation boosts.