Visual programming environment has brought about great changes in the development of human-machine interface. It enables the developers to implement human-machine interface using visual operations by means of “hat you see is what you get? and the program code can generate automatically by the environment. This change gives rise to some new problems to object-oriented design of human-machine interface. Since the implementation of the interface does not depend on manual programming, is it necessary to design before implementation?And whd what is the use of the class diagram built at the design stage?The answers to these questions can be found in this paper.It proves that the design is necessary yetin that environment,but its strategies should be improved.The OOD(object-oriented design)strategies for the development of human-machine interface are given,which makes the OOD work much simpler simpler,more efficent and more suitable for development in the visual programming environment.