Abstract: Virtual disassembly is not only an effective way to assess the maintenance performance of products, but also helps to perform assembly sequence planning of products. Assembly constraints are dynamically released following the user's intention while he disassembles the product interactively. Then, movements of the user's hand in disassembly are sent to the system software through sensors and cause the constrained movement of the disassembling part in the allowable motion space. In such a way, the user can disassemble the parts freely and intuitively. Above-mentioned methods were implemented in the self-developed virtual reality design and assembly system (VIRDAS). Some virtual disassembly examples are illustrated.