One of the solutions proposed to reduce energy consumption in large cities is the construction of a green roof. This research aims to introduce the green roofing system and its role in reducing the thermal energy transfer and the phenomenon of urban Thermal Island, to study the thermal effect of using green roofs Compared to conventional conventional roofing. The research method has been quantitative and analytical research in the areas related to the green, descriptive and qualitative research, and in the software-related areas of quantitative research and analytical method, and to prove the hypothesis that "green roof and its design play an effective role in Reducing heat transfer "has been used to simulate the design of the 1-sheet. A typical roofed roof with some specific details (polystyrene and polyethylene) is analyzed and their heat transfer in four cities representing major climates In Iran (Tehran, Tabriz, Bandar Abbas and Ramsar) has been studied. The results of the research show that green roofs have the most impact on the cold and humid climate (Ramsar) with 22% and the least impact in cold and mountainous climate (Tabriz) with a 14% reduction in energy consumption. In addition, the amount of cooling loss in hot and humid climate (Bandar Abbas) was lower than other three climates of Iran (Tehran, Tabriz, Ramsar) and in cold and mountainous climate (Tabriz) compared to other three climates (Tehran, Ramsar, Bandar Abbas) And also the most reduction in the heating load in the cold and humid climate (Ramsar) and the lowest in warm and dry climate (Tehran).