Benchmarking has been recognized to be an effective analysis methodology and management tool that helps to improve efficiency and performance in many areas for different objectives. Industrial energy benchmarking is a process of evaluating energy performance of an individual industrial plant or sector against a reference plant or sector. Energy benchmarking based on the performance of industry leaders or best practices is particularly useful for identifying energy inefficiencies in the production processes and estimating the potential for energy savings. This paper introduces industrial energy benchmarking and existing programs and practices and then provides a formal general system description of industrial energy benchmarking. Process-based energy benchmarking approach is further analyzed in detail from the perspective of systems engineering. The resulting system description and methodologies provide a general unified framework for analyzing and implementing industrial energy benchmarking. An industrial energy benchmarking prototype is analyzed to demonstrate the basic idea and practices of industrial energy benchmarking within this general system framework.