Based on present research states and new problems of current collaborative design (CD), the paper presents a solution of building Virtual PDM (VPDM) for developing a CD platform on heterogeneous CAD and PDM systems among enterprises. Firstly, VPDM definition and characteristics are put forward, the CD framework in VPDM is proposed and each component of VPDM are analyzed. Secondly, operations and features in CAD are described with Express-G, a unified feature model is built and mapped into database mode. And then, feature-based CD sequence diagram, clients’ status and feature expression are introduced in VPDM environment. At last, prototype system developed using above method makes CD come true in two commercial CAD systems and two commercial PDM systems, which proves that our approach works well.