Abstract: Digital twin is the key technology to promote the development of digitization and intelligence in the field of electric equipment. The relevant research is in initial stage, and how to achieve digital twin of electric equipment is an urgent problem to be solved. This paper describes the intension and applications of digital twin and then summarizes the research and application progress of digital twin in the field of equipment from the aspects of digital twin framework and implementation method, application in equipment life cycle, mainstream manufacturers and their platforms. Secondly, the key technologies of digital twin in the field of electric equipment are analyzed. Finally, an electric transformer is taken as an example, and the implementation method of the electric equipment multiphysics digital twin based on the Microsoft Azure and ANSYS Twin Builder is given. This paper also points out the challenges faced by the digital twin of electric equipment in data collection, model building and solution, and platform use. The recommendations are as follows: developing high-performance sensors and building a reasonable sensor network to enhance the depth and breadth of data collection; developing a full-scale multi-physical field model and real-time solving algorithm for electric equipment; and developing a national digital twin platform for electric equipment performance analysis.