This paper studies the emergent property of complex adaptive system of group behavior driven by the individual by the agent simulation method in an example of urbanization. It is considered that urbanization is a stochastic process of graph. The payoff of an arbitrary city can be regarded as the corresponding payoff coming from the interacting with the other cities, and it must rely on its local topological configuration. Meantime urbanization is also a complex adaptive system. When the system is under attack, it has a strong criticality, and this critical probability of attack relies on the payments of agents in the system.