This article is adapted from the research project of National Science Council-"The Study of Spatial Behavioral Pattern in Open Space" and focuses on the theoretical discussion of open spaces of Taipei area. The first section tries to define the concepts and definitions of open space and introduces the concept of openness" of urban open space. The second part tries to "point out the problems of urban open space of Taipei area, includes. (1) the distribution and quantitative requirements of urban open space, (2) the design criterea on urban open space quality, (3) the potential of urban open space on the implementation of city planning and design.