Driven by the "dual carbon" goals, green construction has become the key path of low-carbon transformation in the construction industry, but in the context of large-scale promotion of green construction, it faces significant constraints due to the blurring of incremental cost accounting boundaries. At present, most of the research focuses on single technology or short-term cost analysis, and lacks the systematic integration of "four sections and one environmental protection", which leads to problems such as cost fragmentation and dynamic accounting imbalance, which is difficult to support the refined decision-making of enterprises. Based on this, research to construct a theoretical model for calculating the incremental cost of green construction in the whole life cycle, and innovatively proposes a logical framework of "measure aggregation-dynamic correction-sensitivity analysis". The results show that the model can not only accurately identify the cost drivers, but also optimize the incremental cost assessment through the dynamic benefit offsetting effect. It not only fills the theoretical gap in the systematic and dynamic collaborative quantification of cost estimation, but also promotes the green transformation of the construction industry and helps the efficient implementation of the "dual carbon" goals.