The energy industry is the largest source of carbon emissions and therefore，a key area of carbon emission reduction. Under the constraints of carbon peak and carbon neutrality goals，it’s urgent for the energy industry to accelerate the transformation towards “clean，integrated，intelligent，and decentralized”. As an important part of the energy system，the electric power system will also face a series of challenges，such as the penetration of a high proportion of renewable energy，the increasing level of terminal electrification，high electronization and the localization of a large-scale distributed energy. The concept of the integrated energy system came into being to adapt to the new situation and requirements of energy and power industry. Integrated energy system refers to the energy system that integrates the production，supply and marketing of various kinds of energy，such as cold，thermal and electric energy，to promote the sustainable development of energy. The development of the integrated energy system will help break the barriers of technology，institution and market among various energy subsystems and realize multi-energy complementation and collaborative optimization，which will effectively promote the clean and low-carbon development of the energy industry，thereby contributing to achieving the goals of carbon peak and carbon neutrality. In the future，the development of the integrated energy system should be accelerated in terms of core technology development，service patterns innovation，ecosystem construction，key disciplines construction，and pilot application promotion，so as to provide new solutions for the clean and low-carbon transformation of the power system.