Abstract: In the report， based on one existing buildings in Haikou， rooftop modern Greenhouse model was constructed， and the simulation calculation were performed， the effects of plants， energy， and water on the carbon emissions of the main building during its life cycle were quantitatively analyzed. The results showed that the Rooftop modern greenhouse with a designed service life of 20 years and an area of 840 m² generates 80 t of carbon emissions during the production， transportation， construction， and demolition stages of building materials. During operation， the main building's carbon emissions can be reduced by 277.02 t， and its full life cycle can reduce the main building's carbon emissions by 199.03 t， which means its carbon reduction efficiency is 237 kg∙m^-2. So， the reasonable construction of rooftop greenhouses can become one of the measures to reduce building carbon emissions and help achieve the dual carbon goals.