Fraction Vegetation Coverage (FVC) is one of the most important land surface parameters. The change of FVC directly affects the redistribution of land surface energy and then affects regional and even global climate change.SStudying the effects of increased FVC on regional climate has great significance for future projections of regional climate change, which is essential for adaptation and mitigation of global warming.SIn this paper, MODIS-NDVI index from 2001 to 2018 were used to calculate the FVC, and long-term simulation experiment of WRF model with default and actual FVC in Liaoning province respectively were simulated. The conclusions show that:S(1) The annual average temperature in Liaoning decreased by 0.48℃ due to the increase of vegetation coverage, with the largest drop of 0.71℃ in summer, 0.35 ℃ and 0.66℃ in spring and autumn, and the smallest drop of 0.2℃ in winter.SThe increase of FVC also had a significant cooling effect on the maximum and minimum air temperature, and the response of the minimum temperature to the increase of vegetation coverage was greater than that of the maximum temperature, and the increase of FVC had a good spatial consistency with the temperature cooling.S(2) The significant increase in annual and seasonal FVC from 2001 to 2018 had a cooling trend on the annual and seasonal average, maximum and minimum temperature, especially on the minimum temperature.S(3) The main reason for the decrease of air temperature caused by the increase of FVC is that the increase of evapotranspiration leads to the increase of latent heat flux and the decrease of sensible heat flux.SFor the minimum temperature, it is mainly caused by the decrease of surface temperature caused by the increase of vegetation coverage and the decrease of upward longwave radiation at night.SIn general, the more FVC increases, the more obvious the cooling effect will be, and the increase of FVC can slow down the climate warming in Liaoning Province.