Considering the characteristics of conceptual design and the feature classification of virtual prototype, this paper presents a novel virtual prototype-based product model, V-desModel, and the description language, VPML, in conceptual design. It introduces virtual feature concept in the product's view models, and employs expandable 3D entity-constraint graph to describe the constraints between design objects. V-desModel and VPML language can effectively support the process of cooperative design and concurrent design, solve the insufficient information problems in constructing virtual prototype during the conceptual design of product. They provide coherent model description for cooperative design, concurrent design, and confederate simulation of multi-discipline systems.