Abstract: Energy flow calculation is the important foundation of the analysis and optimization for integrated energy system, which faces many challenges due to its extensive involvement in the coupling of multiple energy forms, such as electricity, gas, heating,cooling. In this paper, the existing research results are systematically summarized from two aspects: certain energy flow calculation and uncertain energy flow calculation, whose basic theory, mathematical model and solution methods are comprehensively reviewed, as well as advantages and disadvantages are compared. The certain energy flow calculation aims to obtain the operation state under a certain working condition based on the known information solution system, and it is discussed from two aspects:steady-state calculation and dynamic calculation. The uncertain energy flow calculation aims to obtain the system state distribution characteristics under the influence of uncertainties based on the certain energy flow calculation, and it is discussed from three aspects: probabilistic energy flow, interval energy flow and fuzzy energy flow. Finally, the research areas of energy flow calculation are prospected according to the requirements upon the development of integrated energy system.