To deal with the deep penetration of renewable energy in the power grid and energy coupling in the distribution and consumption part, improve energy efficiency, and construct the regional integrated energy system (IES) with multiple self-sufficient cells, energy cell has attracted widespread interest. However, the different management systems, diversified energy features, and information barriers increase the difficulties of unified energy flow calculation of IES. Based on the theory, this paper proposes a parallel distributed computing method for multi-region IES with electricity network being considered as a dividing surface. First of all, the basic principle of energy cell is proposed and the large-scale IES is divided into several energy cells according to the energy balance ability and geographic location. Then virtual nodes are added at the boundaries of the energy cells and the adjustment factors are introduced to ensure system convergence. Moreover, the extended Jacobian matrix was constructed to calculate muti-energy flow (MEF) in a single energy cell and decoupled energy cells can be computed in parallel through the limited information exchange of virtual nodes. Finally, two cases are utilized to verify the performances of the proposed energy method. Comparing with the integrated method and the decomposed method, the proposed method in this paper has better abilities in calculation efficiency and accuracy.