The intensification of the global environmental problems is raised as one of the subject that the mankind have now in the 21st century. The global warming by the discharge of carbon dioxide and energy use, as an urgent subject, has resulted in a global interest as been seen in the World Environment Kyoto Conference etc, that was held in December, 1997. On this kind of background, the distributed combined heat and power generation has been expected to improve the energy and environment problem. Combined heat and power generation allows to reach efficiencies which can be as high as 85-90% for both products and result in substantial energy and CO_2 savings. There is yet little research that is how much the influence to the contamination, heat, wind environment become, although the research are carried out numerously with regard to such an economic and efficiency face with introducing combined heat and power generation system conventionally. This study is to evaluate the influence to the environment by the introduction of combined heat and power generation system by the simulation of the heat and atmosphere environment. A case study has been made in the Kokura area of Kitakyushu-shi.