The management of the design process is a challenging mission; and most researchers would argue that design is linked to intentional action and it cannot emerge out of complexity. In fact, the interactions between processes, operators, and activities define an unexpected emergent behavior, which is based on complex assumptions such as non-linearity, dynamic and adaptive firm behavior. Therefore, we need a complex thinking. This article proposes to explore how we may deepen our understanding of design process as a complex adaptive system. In fact, this new understanding creates a quite challenge for researches to develop appropriate tools to support design reasoning and decision-making. In this respect, the aim of this paper is first to define the complexity of design process as a complexity of system, by matching its characteristics with those of complex adaptive systems (CAS). Second, the paper provides an agent organizational modelization of the design process in order to support its complexity by following the ASPECS methodology which is an agent-oriented software process for engineering complex systems as well as the knowledge identification of the design process using the RIOCK meta-model.