This paper presents a noble operation and maintenance system for the optical subscriber loops and its feasibility through several experiments. In this system, a broadband CW (Continuous Wave) light source I used as monitoring of testing signals. and a FGF(Fiber Grating Filter) of which reflective wavelength is independent, is inserted somewhere in each subscriber loop for the reflection of monitoring of testing signals. The propose of the system is quick decision. whether the loop is just fault or not. rather than detailed information of loop state. At present, most of operation and maintenance system for the optical subscriber loops adopts OTDR(optical time domain reflectometer) for testing function. the OTDR is useful for detailed test, but not adequate for simple test because of long testing time . And it is difficult to test PON network by using general OTDR that has a single-wavelength light source. Compared to using OTDR, the proposed system can afford to shorten testing time and to test PON network. Moreover, we can cut down the system cost by simplifying circuits of the optical light sources. Our results show that the proposed system operates well according to the purpose mentioned above.