Virtual assembly (VA) is a key technology for virtual manufacturing systems. So far, CAD systems are still the main modeling tools for the VA system. There isn't a standard data exchange criterion to transfer the data directly from CAD systems to VA applications, consequently an original data decomposition and information translation method (DDITM) was timely proposed to achieve the decomposition and translation. The information of the assembly bodies in the CAD system was divided into geometry information, topology information, and assembly information, etc., which were transferred to the VA application separately. The geometry information including the surface information was translated by the data translation interface (DTI) developed, the topology information was translated by a fivehierarchy topology structure (FHTS) constructed, and the assembly information was translated with database technology. A systematic architecture was formed with the interaction between the geometry information and the topology information, and the assembly information and the topology. Finally an experimental VA system was set up to verify the DDITM, and an assembly simulation was implemented to verify the assembly information further, which proves the translated information is precise and sufficient.