Abstract: For purpose of locating part model precisely in a virtual environment,this paper presents a motion guidance method based on frame theory.A process frame encapsulates knowledge about typical assembly processes,and relevant engineering information in the parts' B-rep models is transformed to the feature frames which describe part structure from the assembly view.A frame-based system is composed of the process frames,the feature frames and an assembly scene matching engine.Manipulator's assembly intentions are perceived by the scene matching engine.The system makes use of the matched process frames to guide the assembly process.The parts are located precisely by implementing actions that are described in the matched process frame.Application results show that the problem of controlling the motion of the assembled parts precisely with current virtual reality I O devices during virtual assembly is resolved effectively.