Abstract: Based on the dual computer synchronized desktop virtual reality equipment, a virtual assembly system for the complex products was introduced. The human-computer interactive technology in the system was studied. The product information management technology was proposed on an algorithm of the SOP (structure of parts) data construction which acted on the attribute class for driving. The DOF (degree of freedom) law for matching the rotation center of models was presented. A direct and fast control interactive algorithm principle which was suitable for the multi-parts and multi-scenes grounded on the LOS (line-of-sight) technology was discussed, and the usability and efficiency of the algorithms were verified through the system realization. It is proved that the performance and extension feature of the system were promoted obviously.