Abstract: Assembly constraint is the key information for supporting the assembly operation in distributed virtual environments. The abstract of assembly constraint is related to the support capability of the assembly unit's actions. And the structure mechanism of assembly constraint determines the efficiency of the implementation of distributed virtual assembly. To solve the existing issues on the abstract and application of assembly constraint, firstly the semantic abstract and expression of assembly constraint are studied and used to capture the knowledge from the application field of mechanical product assembly and induce the basic semantics of assembly constraint. Secondly, an extended object semantic modeling method is brought forward, which structures the assembly constraint with the function and behavior characters, and constructs assembly constraint semantic models. The experimental result of the VEADAM system shows that the assembly constraint semantic models can effectively support the implementation of distributed virtual assembly and can adapt to the variety of applications.