In BIM (Building Information Modeling) application system, the real information of building components is described by a series of digital object attributes and relationships. These object attributes can be independent of each other or interrelated according to some customized rules, so they are parameterized. This scheme integrates the information structure, excavates the data value, has the advantages of strong standardization and high compatibility, and brings efficient and stable energy-saving benefits for building operation and maintenance. The application architecture and functional modules of lightweight BIM architectural design system based on building big data are designed. The overall architecture is divided into data acquisition layer, data processing layer, data analysis layer and application layer. The hierarchical architecture is used to separate the storage and utilization of model information, the information is integrated and managed by database to realize the sharing of model information, and the graphic platform is used to display the data graphically. Experiments show that the algorithm proposed in this paper has a good lightweight visual optimization effect for large-scale BIM 3D scenes. The reliability and practicability of the system are verified.