A system modeling facilitating method and apparatus, wherein, entities and interactions among the entities are introduced gradually starting from critical entities in a system to form an abstract view of the entities. An associated sub-module is built for at least one of the entities and interfaces to other entities are formed for the sub-module. Representations of behaviors and logical relations among the behaviors, as well as links between its interfaces and representations of behaviors are built. When an entity is extended to be a sub-module, other entities appear in abstract form, forming a local view of sub-module together with the other entities shown in abstract form. A global view can be formed by combining the sub-modules depicted in the local view based on the interaction described in the abstract view.