Agricultural facilities can be designed by conceptual preliminary primary and detailed design stages. because each stage has a different objective, it must be applied to dissimilar design and analysis level. Engineers have to judge from evaluation that is estimated agricultural resources in the conceptual design stage. Methods of computer aided design are achieved to individual functions however it is inefficient to perform entire processes of design and hard to systematically accumulate results o design. Study on the integrated structural design system has been continued. but those system have adopted “closed architecture”which is known to inflexible method for developing applications. In this study the design platform is an environment that can support to integrated design system independently and an design platform is proposed by analyzing design processes using object oriented method. The concepts of software platform have resulted from several practical ideas, OOA/OOP and related some points. This paper aims at developing the software platform of a software environment to support the design phases of the agricultural facilities.