Abstract: An integrated energy system（IES） involves many different forms of energy, and exergy can be used as a measure of energy quality. Based on the idea of“flow”, a modeling method for the exergy flow mechanism in the IES network is proposed.First, the exergy flow analysis scope is defined based on the energy flow. The exergy flow mechanism of the heat system is analyzed. The concepts including exergy-potential and exergy-potential difference of heat system are defined. And the exergy flow mechanism model of the heat system is established. Then, the relevant laws are extended to other energy networks, and the concept of exergy-potential and exergy flow mechanism model of power systems and natural gas systems are proposed. The energy station is equivalent to an exergy loss node, and the advantage of the exergy flow mechanism model is verified through the exergy balance analysis of each link. Finally, a test system is given to intuitively show the exergy flow distribution of IES, and the exergy loss of each link is analyzed. By analyzing the overall and local exergy balance relationship, it is verified that the exergy flow mechanism model has more advantages than the traditional black-box model. The advantages of applying exergy flow theory in the high-quality energy system are discussed.