The characteristics of multi associations business coordination among the enterprises in industry chain is firstly analyzed, and the demand of customizable business of SaaS(Software as a service) based platform supporting the industry chain coordination (in brief, PLATFORM) is intensively analyzed. Based on these, customizable business-oriented PLATFORM architecture based on SOA is designed in the paper, which takes support layer as the foundation, takes bus layer and service layer as the core and takes customizable application layer as the target. Based on the architecture, application layer can provide simple, convenient, rapid support for SaaS based business customization and system applications, based on the rules of dynamic union building, business functions configuration and personalized functions configuration. Application results show that the customizable business-oriented architecture of PLATFORM proposed in the paper can well satisfied a variety of requirements for customizable business due to the business characteristic includes variability, dynamic and multiplicity from different alliance enterprise in the PLATFORM.