Abstract: It was studied particularly the inner public space of an office building, which was used for the sharing and communication. Firstly, it was expounded the importence of the inner public space. Secondly, analysed the design technique of archi structure, based on the character and conformation of the inner space, combining with the design scheme of relevant projects. Finally, it was also summed up the trend of its development, which provided a theoretic reference for the design of similar projects.