Land use and land cover change influences regional climate through both biogeochemical and biogeophysical processes. Afforestation has been one of the most intensive human activities on land cover. It results in the increase of carbon sequestration and has been proposed as a most effective strategy to mitigate climate change. However, considering only carbon storage would lead to underestimation or overestimation of the impact of afforestation on climate regulation. This paper aimed to disclose the impacts of returning farmland to forest on regional temperature by the carbon budget and surface energy balance in different climatic zones. The results showed that if only the carbon regulation effect was considered, the returning farmland to forest was in the carbon sequestration process with 241.6-470.2 Mg CO_2-eq hm~(-2), and was carbon sinks of 2.2-16.5 Mg CO_2-eq hm~(-2) in various climate zones, which means the cooling effect on air temperature, especially in subtropical and humid regions. If only the biophysical process was considered, the returning farmland to forest in northern arid and semiarid regions resulted in more increase in net radiation than increase in latent heat flux, so the returning farmland to forest had warming effect on temperature. However, it resulted in decreased net radiation and increased latent heat flux in southern subtropical regions, and less increase in net radiation than increase in latent heat flux in Tibetan Plateau and temperate humid regions, so the returning farmland to forest had cooling effects on temperature in those regions. Therefore, when taking into account both the carbon regulation and land surface energy balance, the cooling effects of the returning farmland to forest in southern subtropical regions is 1.25 to 1.45 times more than that when only the carbon regulation was considered, while the cooling effects in northern arid and semiarid regions is about half of that when only the carbon regulation was considered.