Abstract: The design and implementation of the domain-oriented designing and modeling tool, SIMDEMO, were discussed. A cooperative modeling methodology supporting multi-views modeling was built by decomposing system models which involve various modeling stages, users, aspects into multi-views based on principles of transparency, orthogonality and hiberarchy, and the guidelines for the modeling processes were also presented. In consideration of the different needs for the description, representation and operation of the models in different domains, a reflective architecture based on the meta-object model was built; The architecture has good adaptability, and can make the customization of the tool more flexible and concise. The system structure and functions were introduced briefly, and the software implementation was presented. At last, SIMDEMO was compared with the similar representative tools.