On the basis of product 3D model which links with the process of design, 4D Information Model as a structured integration of product information need to express all the complicated relationship between product information and keep the consistency of all these relationships in the whole product evolving process.[1]. Based on the analysis of the information character in product design process, the design process information of 4D Product Information Model (4D-PIM) is elaborated by introducing hypergraph theory. The theory basis for establishing 4D-PIM is studied, and a formalized description of 4D information model is carried out. The paper provides a new research method to product design and the process management of it.