In steel enterprises, the design of energy systems mainly depends on experience and lacks systematic optimization methods. Therefore, it is of great significance to propose an overall optimization design method for the energy system of steel enterprises. In this paper, a linear model is proposed to select the energy conversion equipment types and distribute energy sources with the aim of maximizing the economic benefits of an energy system. In the model, the choice of energy conversion technology and the distribution of energy source are considered comprehensively. For the S steel plant, the case analysis results show that under the condition of keeping the original energy conversion equipment unchanged and optimizing the distribution of energy source, the economic benefits of the energy system can be increased by 15.77 CNY/t steel, and under the conditions of optimizing the distribution schemes of the energy conversion equipment types and energy sources, the economic benefits of the energy system can be increased by 180.26 CNY/t steel. In addition, the effects of different energy conversion equipment configurations, different energy sources prices and different pollution cost standards on the steel plant energy economic benefits were analyzed.