Abstract: VSML(Visual System Modeling Language) is successfully used for describing computer-based application systems from functions, behaviors, data and architecture, and supporting object-oriented rapid prototyping and software reuse methods.VSML's design considerations, the definition of primitives, the behavior description rules and the improvement of database access functions are firstly introduced, then its architecture and application in the development about MIS are described in detail. Finally, a conclusion and thought for further study about VSML are given out.