In order to promote the informatization process of road and bridge construction and improve the management level of road and bridge construction, parametric bridge modeling technology is studied in depth. In this paper, through an in-depth analysis of the working principle of the Revit-based visual programming plug-in Dynamo, combined with the application examples of parametric modeling, a method of parametric modeling of the precast box girder BIM model based on the Dynamo plug-in is proposed, and the BIM model of the precast box girder is realized. The rapid and accurate modeling avoids the error caused by the direct substitution of the curve in the modeling process of the prefabricated box girder of the relaxation curve section, which greatly improves the modeling efficiency and modeling accuracy, and provides technical support for the BIM modeling work of similar projects.