Abstract. In today's dynamic IT environment with increased global competition, enterprises must achieve greater business agility and decrease the TCO (Total Cost of Ownership) of their system for service. As the need for innovative software circulation process emerges, SaaS (Software as a Service) is introduced for integrating software service framework. But most of current ASP (Application Service Provider) Players have difficulties to migrate their systems to SaaS Platform for the lack of maturity model and process. In this paper, we have surveyed several cases of SaaS service, and we identified the common key functions of SaaS service. We contend that the practical maturity model is a key enabler for achieving migration to innovative SaaS service platform. To assist in building our SaaS maturity model, we defined two important axes of maturity model and introduced the detailed components of each phase with the reference architecture which contains the essential activities accor...