Recently, with the enormous proliferation of smart mobile phone devices. smart device platforms have became diverse and the complexity is accordingly increased. Unfortunately, however, there is a problem of interoperability and portability among applications. Because of this, a novel platform-independent application development method is needed, and the requirement of the cross-platform environment is on the rise, However, cross platform environments that can flexibly handle new or unthought-of platforms have not been suggested yet. Therefore, we propose a MDA(Model Driven Architecture)-based smart platform application authoring tool architecture for a cross platform environment. The proposed authoring tool architecture will provide the portability, interoperability, and reliability by employing PIM(Platform Independent Model), PSM(Platform Specification Model) and UML(Unified Modeling Language) profile.