With the promotion of national energy policy, integrated energy system are developing rapidly. In order to better regulate energy and manage energy use in integrated energy system, calculating the flow of various types of energy in integrated energy system has become a priority task. The coupling relationship between the energy in the integrated energy network makes it difficult to converge the large-scale calculation, while the difference in the time scale of energy also makes the calculation of energy flow difficult. Therefore, in this paper, a decoupled distributed calculation method is proposed to address the problems of high energy coupling and computational difficulties in the calculation of energy flows in large-scale integrated energy system. The method decouples the coupled nodes of the integrated energy system, decomposes the network into approximately independent energy system, and proposes a parallel and synchronous computation method to improve the computational efficiency of the integrated energy system.