Abstract: A method of realtime computing the gap among objects for interactive virtual assembly was proposed. In this method, a single or a group of bound box is confirmed firstly based on getting the minimum distance among the hierarchical bounding volume（BV）, as result the nearest goal polygon group is gotten. Then the minimum distance and location of the gap are calculated. This method has the advantage of being able to use the hierarchy collision detection model existing in the virtual assembly environment, as well as parallel computing system. The method is integrated in DPVAE (distributed parallel virtual assembly environment) system and verified with application of dynamic gap computation of car rear suspension assembly. The result shows that the method can be used for space analysis in realtime interactive virtual assembly operations environment.