Abstract: By researching on the historical plans of Washington open space system, this paper describes the successive process of the Washington’s open space system starts from L’Enfant’s grand Le Notre plan for the country’s ambition, to the McMillan Plan that meet the challenges of urban issues of the industrial era, and to the optimization and consummation of multi-functional open space system in the post-industrial era, reveals the development and perfection of the open space system in Washington. This paper also analyzes essentials on open space system’s plan strategies toward transformations in different times, interprets the continuity feature in long planning process, finally sums up the experience of plans for Washington’s open space system, to provides effective references for urban construction in China.