Abstract: Defining the product from the angle of industrial ecology, the three indices of eco-efficiency are given, i.e., resources efficiency, energy efficiency and environment efficiency, to analyze the eco-efficiency of steel industry. Taking the data of a steel enterprise as example, an input/output balance sheet was worked out by way of industrial metabolism to make sure of the sorts and amounts of resources, energy, products, wastes and pollutants and analyze the eco-efficiency of the steel enterprise. Discusses the influence of symbiotic relationship among the wastes/pollutants utilized mutually by different enterprises on the three efficiencies mentioned above. It was found that the formation of such a symbiotic relationship is an important way to solve the increasingly serious problems of resources, energy and environment in China's steel industry.