Bayan Obo mine in China is the largest iron-niobium-rare-earth symbiotic and associated mine in the world. Its exploitation has brought great economic benefit over the years. At the same time, many environmental problems arise. One of the most serious problems is tailings. Based on the theory and method of life cycle assessment, the environmental problems caused by integrated exploitation technology for tailings in Bayan Obo mine have been studied. Environmental impact assessment method TRACI 2.1 developed by Environmental Protection Agency of the United States has been chosen in this study. Through the study of resource consumption, energy consumption, pollution input by raw materials, pollution from industrial emissions etc. of each process, 10 types of environmental impacts have been studied and their values have been calculated. Results show that the main environmental impact types are Human toxicity non-cancer, Human toxicity cancer, Ecotoxicity, Global warming air, Human health particulate air, respectively. And the pollution input by raw materials is much greater than that from industrial emission, which provides a typical case and support for green purchasing, green manufacturing, process improving etc.