Abstract: This paper proposed a real-time carbon flow calculation method based on network power decomposition, which aims to solve the shortcomings of the traditional methods that cannot guarantee the fair distribution of carbon flow. Based on the lossy network and adopting the idea of complex power tracing, the branch loss can be modeled as a virtual power supply or load to form a lossless network. By introducing an adjustable distribution coefficient, the upstream power tracing and downstream tracing are combined to realize the two-way allocation of network loss carbon emission. Considering the imbalance of real-time carbon flow allocation, each renewable generation unit is treated as a load, and the real-time power network is decomposed into the basic power network and power deviation network. Then, the basic value and correction of carbon flow are calculated respectively, so as to obtain the actual carbon flow distribution with fair apportionment guaranteed. The test results show that this method can improve the accuracy and fairness of carbon flow allocation. Moreover, it can effectively solve the problems of the inability to quantify the contribution of renewable energy to carbon reduction and the difficulty in accurately measuring the implicit carbon emissions, which has certain practical value and reference significance.