It looks back policy bank history development stage and point out the new current in western countries . moreover , it describes the major base and function of policy bank . secondly it analyzes policy bank " 4 foundamental characteristic ; they are including characteristic of ownership , chracteristic of business and characteristic of purpose , characteristic of function 回顾了政策性银行的三个历史发展阶段及当代西方政策性银行发展的新趋势，同时从业务、范围、组织结构、服务方式等角度对政策性银行进行分类，阐述了政策性银行存在的主要依据和职能，指出政策性银行是市场经济发展到一定阶段的必然产物，以此作为展开全文讨论的基础铺垫。
