Abstract: The old city is the matrix of a big city. With the acceleration of urbanization, the urban population and vehicles are increasing. The original traffic cannot meet the existing needs. Just like the old city of big cities in the world, the old city of my country At a certain stage of urban development, there has also been a phenomenon of upgrading traffic light intersections to full interchanges, and the densely planned underground pipeline network in the old city has become a major constraint in the construction of the overpass upgrading project. This article combines the development of BIM technology in the all-interchange upgrade project of Bingui Road, Nanguo Road, Shunde District, Foshan City, analyzes the characteristics and concepts of BIM technology, and discusses the improvement of BIM technology in the old urban area from the construction preparation stage and the construction stage. Construction application of engineering projects.