Abstract: For the description of dynamic behaviors of software systems, some important existing models are analyzed and compared, including algorithm models, logic models, models, and formal calculi based on process algebra, I/O automata, Petri nets, and actor models. In addition, some crucial properties of object interactive systems such as interaction, concurrency, and distribution are also discussed. As part of a larger project which focuses on the direction of component software theory and design methodology, this work will help to clear the concept, consolidate the understanding, and lay down a deep foundation for the research on model and semantics of distributed object computation and the specification and verification of an object system.