The resource utilization of construction waste has significant carbon reduction and low-carbon demonstration effects. However, the development of related emission reduction projects lacks applicable methodologies. This study aims to develop a carbon reduction accounting methodology for the replacement of natural aggregate with recycled construction waste aggregate. After defining the scope of application as the project activities of construction waste resource utilization factories, the methodology development adopts obstacle analysis method to identify and demonstrate the baseline scenario, and uses the difference comparison method of baseline and project emissions and the carbon emission factor method to calculate the emission reduction. The monitoring method specifies the parameters and data required for the design and implementation phases, with a focus on monitoring the various energy consumption, waste treatment volume, and recycled aggregate output of the production line during the implementation phase. The study verified the effectiveness and feasibility of methodology using a real project in Jiangsu Province. The results of this study not only fills the gap in the methodology of voluntary greenhouse gas reduction in the field of construction waste resource utilization, but also enriches the market-oriented action plans for the resource recycling utilization of construction waste from the carbon reduction accounting perspective.