The invention relates to a point-to-point optical fiber online monitoring system and method. The system comprises a protection device, an online monitor and an intelligent terminal. The intelligent terminal is provided with an optical fiber communication interface, a network monitoring communication interface and a message forwarding processing module. The protection device is connected to the optical fiber communication interface through a point-to-point optical fiber. The message forwarding processing module is connected to the optical fiber communication interface and the network monitoringcommunication interface. The network monitoring communication interface and the protection device are connected to the online monitor through a process layer network. The protection device sends a tripping and closing GOOSE message to the intelligent terminal through the optical fiber communication interface. The online monitor obtains the tripping and closing GOOSE message from the process layernetwork. The intelligent terminal sends a feedback GOOSE message to the online monitor through the network monitoring communication interface. The online monitor compares the feedback GOOSE message and the tripping and closing GOOSE message so as to complete the point-to-point fiber monitoring. Compared with the prior art, the monitoring method of the invention is simple and reliable.