This paper proposed a reference model of independent SaaS platform. Firstly, SaaS software's technical architecture is discussed. Secondly, SaaS platform's responsibilities are analyzed and the infrastructure components of independent SaaS platform are presented. We propose a concept of multi-tenant architecture. Both the vendor and the user pay for using the platform in an on-demand fashion. Finally, we summarize the advantages of independent third-party SaaS platform. By such a SaaS platform various vendors will profit greatly and customers will get the best software services.