The stability of supply and demand network with multi-functional and opening characteristics for enterprises SDN is essential to its vitality and development. The cooperation relationships among enter prises in either one-short static state game in traditional enterprises or finitely repeated games in supply chain are inefficient. Infinitely repeated game and grim strategy that can lead to Pareto dominance Nash equilibrium are the deep economic reasons which explain the stability of SDN. The paper will demonstrate the stability of SDN in detail through building the economic model of cooperation relationship among members in SDN.