This paper uses the theory of Institutional change as research tool to analyze from the angel of informal rules, formal rules and enforcement system, which is fresh. The conclusion from the thesis is pointed. 本文运用诺斯的制度变迁理论作为全文的分析工具,从非正式规则、正式规则、实施机制三个层面展开全文,具有新颖性,而且分析工具贯穿全文,得出的结论具有针对性。