Abstract: With the advance of the national carbon peaking and carbon neutrality goals, the traditional power system has been transformed and upgraded to the form of new electric power system. The digital transformation of power grids is considered as an essential support of the carbon goals. The advanced metering infrastructure, taking smart meters as the core, can provide magnanimity operation data of all sectors in power systems. With the deep integration of energy and information, the information entropy can mine the information value hidden in energy data, thus improving the safety and economic benefits of energy systems, as a simple and direct measure of the amount of information. The key concepts, relevant concepts and special concepts of information entropy in power system are summarized in the paper. A novel taxonomy considering both the physical nature of information entropy and characteristics of power systems is proposed, based on which a literature review of information entropy in power systems is presented, from the perspective of signal complexity, value diversity and objective similarity, and divided into three application fields: protection and control, dispatch and operation, planning and evaluation. Challenges and future research trends of the information entropy in power systems are discussed, taking energy an d economic data analysis as an example, combined with the discussion of extended research of entropy in other fields.