Abstract: At present, the production of reinforcement in China is still in the state of traditional on-site processing, which possesses a series of problems, including high waste of materials, high labor intensity, long processing cycle, chaotic on-site management, high processing cost and difficult control of safety quality. Concentrated NC machining of steel reinforcement is an effective way in construction engineering to existing problems of waste of raw materials, high processing cost, and difficult quality and safety management. The application of BIM of powerful and professional technology in the NC machining of steel reinforcement is able to form a BIM-based NC machining of steel reinforcement mode, which can be applied in large-scale and intensive housing construction projects to significantly improve the management level and economic benefits of the project. Taking the transformation project of Xichang PPP shanty towns as an example, this paper expounds the innovative mode practice of construction of BIM-based NC machining mode of reinforcement, which has successfully and effectively solved the difficulties in the traditional steel bar processing, reduced construction costs, and improved construction efficiency and engineering quality.