Abstract: Energy system integration connecting electricity, natural gas, heat, and transportation systems is a possible way to flexibly and cost-effectively drive the energy transition. Current research still needs more quantitative evidence on the performance of future integrated energy systems to achieve policy goals to support this view. This paper first identifies the expected changes in energy systems at integration and proposes a complete energy system approach to evaluate integrated energy systems, including multidimensional, multidirectional, systemic, future, comprehensive, and applicability characteristics. Based on the identified characteristics, this paper reviews existing frameworks for evaluating energy system sustainability and qualitatively evaluates their adequacy for evaluating future integrated energy systems. The findings show that the existing frameworks are difficult to assess the performance of integrated energy systems and that a single set of characteristics cannot meet the diverse needs of energy integration today. Finally, a holistic evaluation framework based on a systems analysis approach and an indicator-based evaluation method is proposed, in which the six features covered are able to evaluate multiple perspectives and objectives at different system levels. In addition, the framework captures future changes in the overall energy system architecture and highlights the interdependencies between energy systems and can be systematically applied to various scenarios in different contexts.