Abstract: Formr finding is the first step in a membrane structure design, which is paramount for the structural performance of a membrane structure.To understant the principle of form??finding, there are four questions being discussed, that are the relationship of form and pretension, four basic types of membrane structures, some rules for form??finding and numerical methods. Moreover, this paper also introduces some architectural requirements which should be considered during formr finding stage, such as drainage, fire, lighting, acoustic, thermal insulation, and so on.