With the rapid development of urbanization, the urban heat island effect has exerted a great influence on the lives and productivity of urban residents. Many research has suggested that the cooling effect caused by vegetation and water bodies is an economic way to efficiently and substantially mitigate the urban heat island effects at a local scale. However, because the previous studies mainly concentrated on a limited number of urban parks, the past result might have a large uncertainty. Since plain afforestationwas implemented in the Beijing Project from 2012 to 2014, 10,648 forest patches have been constructed, therefore providing a great sample for examining the cooling effects of artificial forests.We analyzed the cooling effects of these artificial forests using the land surface brightness temperature as an indicator of urban heat islands. For this, we used the LANDSAT-8 images of 4 September 2014 and additional information about the originally afforested patches. The artificial forests in this project decreased inbrightness temperature by 1.023℃,despitethe short afforestation period. The latter can be explained by the large young plants that were used for the afforestation, as well as the special implementation mode used. A buffer zone analysis showed that the influence of this cooling effect reached as far as 350m from the edge of the artificial forests. The strongest cooling effect was found within 100m from the forest edges, with a decrease in brightness temperature of 0.392℃.In addition, a zonal analysis showed that the artificial forests had the most significant cooling effects in the Yanqing Basin, with a cooling of 3.519℃. The smallest significant decrease, 0.111℃, was found within the 6th Ring Road. An analysis between different years showed that the landscape pattern of artificial forest patches, as well as wetland protection and construction,were important for establishing the cooling effects. According to a patch size frequency analysis, the small patches had the highest frequency, whereas the middle and small patches covered a large part of the total area. Nevertheless, the large artificial forest patches had a larger significant cooling effect compared with the small ones. According to the primary valuation,the cooling effect of this project had a value as high as 488 millionCNY. Approximately 54% of this total value was caused by cooling within the forest patches, whereas cooling within the influential range from the forest patch edges caused approximately 46%.For further afforestation intended for effective mitigation of the urban heat island effects, several factors should receive careful attention. First, large artificial forest patches are preferablein terms of forest patch design. Second, for the configuration of the forest patches,two adjacent forest patches should be between 100 and 500m apart, in order to benefit from the cooling effects of the forest patches'influential range.