Based on the analysis of the parametric generative design method and the advantage of Dynamo, which is a parametric programming plugin of Revit, this article takes a prefabricated parking structure as an example to study its generative logic, group the similar components and present four important links of the process. Consequently, the programme can automatically generate a 3D model by inputting any length, width and height and control a component precisely through parameters, which is the foundation of the realness and integrity of the information transmission and 3D printing of components in the future.