Payload supported bay (PSB) is an important structure between launch vehicle and spacecraft(SC), the vibration characteristics of PSB is a factor which must be considered in mechanical environment design. In this paper, the dynamical performance of PSB was studied for vibration environment control. A method to improve the mechanical environment of SC based on the research of PSB vibration characteristics was presented. A test for mechanical properties of structural material was introduced to build finite element(FE) model. The vibration environment of SC assembled on different PSBs which are made of different material was computed and compared. The influence of structural connection form between PSB and SC was also investigated. Further research was provided on the basis of the analysis results.