One of the important improvements of Flex 4 is to provide a new component and skin architecture. Skin architecture is based on a clear separation of logic and components of visual elements, and creates a smoother work flow between designers and developers. This paper mainly studies the application of skin mechanism in topology graphic system. Firstly, this paper introduces the principle of skin mechanism, then describes the usage method, finally introduces the advantage of skin mechanism according to the realization of a general topology graphic system.