Abstract: A lightweight file format is presented for quickly browsing 3D product model.It is composed of display information and geometry information.The display information is represented by triangles of faces and polylines of edges,organized in the hierarchy of assembly,part,face,line segment and point.Geometry information is appended onto the display information to provide precise definition of geometric elements for inquiry.Files are compressed by geometric approach to facilitate release over Internet.The implemented 3D browsing system offers interfaces to work with data files of popular 3D CAD systems.