By the fine design of BIM and using a unified data source, the sustainability of the whole process of the design data can be maintained, the design can be optimized, and the design works can achieve the requirements of green building. Besides, digital simulation software are used to stimulate and analyze the lights, the winds, the environments, the load, and the personnel evacuation through Ecotect, Fluent, Abaqus and Pathfinder. The results of simulation can optimize building window, the building shading, the building aseismicity, and the evacuation of buildings and renewable energy utilization as well. This method not only improves the design quality but also ensures the design of safety and energy saving, and eco-friendly sustainability, which facilitates the library′s indoor and outdoor environment for both study and life, and thus realizes the harmony among human beings, the architecture and the nature.