The issue of energy has always been the focus of the international community, on the one hand, because of the limited and scarce energy, on the other hand, because energy is of great significance to the sustainable development of human society. This paper mainly studies the DEA model under thermal automatic control and the improvement of energy efficiency. This paper first defines the concept of energy, classifies energy, and analyzes the theoretical basis of energy efficiency. The DEA model and SBM model are explained in detail. The Three-stage DEA model is optimized by using the SBM model. The optimized model is used to study the energy efficiency optimization of company A. through the research results, it can be seen that the Three-stage DEA model can be used to optimize the inefficient workshops and key redundant inputs of company a, so as to achieve the effect of optimizing redundant inputs and improving workshop efficiency.