Software-as-a-Service (SaaS) is a new research orientation for developing software, and has multi-tenancy architecture and customization features, which are very suitable for performance and benchmark test of OLTP transactions. And Bank Intermediary Business (BIB) is the most important business of Bank financial system. This paper focuses on establishing the SaaS-based BIB performance and benchmark architecture and proposes the SaaS-based BIB Database Model (SaaS-BIB-DM), the architecture layer (SaaS-BIB-AL), the data flow view (SaaS-BIB-DF) and the representative transaction model (SaaS-BIB-TM). The database is further extended with the SaaS hybrid two-layer partition methodology and the performance is proved to be better than that in three-tier C/S architecture. And the specific SaaS-based BIB architecture which we proposed is 4-level SaaS-based architecture. Based on the analysis the state-of-art of BIB and SaaS, the paper further investigates future trend of SaaS-based performance testing architecture and benchmark.