自从科斯在《企业的本质》提出交易成本以来 ,传统的经济学一直用这一理论来解释企业代替市场的原因 ,本文试图把科斯近理论用来解释帕累托效率和经济制度变迁的理论 ,说明在交易成本存在的情况下 ,现的经济只能达到帕累托“次”优 ,而非理想中的帕累托最优 ;同时 ,交易成本的存在也会延缓制度的变迁 ,从而不能实现理想的制度演化 Since Coase put forward the transaction cost in the essence of enterprise, traditional economics has been using this theory to explain why enterprises replace the market. This paper attempts to use Coase’s theory to explain the theory of Pareto efficiency and economic system changes, This shows that under the existence of transaction costs, the current economy can only achieve Pareto “second best” rather than the ideal Pareto optimality. At the same time, the existence of transaction costs will delay the institutional change and thus can not be achieved Ideal system evolution