To limit the number of components in the protection switching process and to accordingly reduce the protection cost, a new reliable Wave Division Multiplexing/Time Division Multiplexing Passive Optical Network (WDM/TDM-PON) architecture with cost-efficient hybrid protection was proposed. Firstly, the logic decision unit, protection path control unit and backup transceiver unit were designed in Optical Line Terminal (OLT) to only switch failure components to their backups in Wave Division Multiplexing (WDM) segment. Secondly, by employing the cross bus structure in Time Division Multiplexing (TDM) segment, fast protection switching was achieved in a distributed manner. According to the analytic results of the hybrid protection, the proposed architecture can provide fast and full protection in recovery time of 1.5 to 2.4 ms against Feed Fiber (FF), Distribution Fiber (DF) and Last Mile Fiber (LMF) failures. Certainly, the proposed architecture can also significantly reduce the protection overhead, and achieve great scalability.