To develop the web-based visual assembly system,the technology based on Java3D and VRML is discussed.VRML files are imported to the scene graph through the Loader interface.Then this paper researches on the method of applying the swing event model of Java and the Java3D objects such as Interpolator and Alpha to realize the interactive virtual assembly.Finally,the assembly of a rotor in an electric machinery is given as an instance to illustrate the interactive visual assembly environment based on VRML and Java3D.