This paper, which studied the structure of CAD/ CAE system, has proposed a universal CAD / CAE integration framework. This system, with good compatibility and being convenient to be used, can be the basic platform for all CAD / CAE systems. This framework, with a unified structure of command processor, the message processing system, selection mechanism, can transform the development of CAD / CAE integrated system to that of functional command module. With the help of this framework, functional development no longer relies on framework. Therefore, the framework greatly enhances the efficiency of software system development.