The invention discloses an optical fiber communication-based bilateral inter-tripping device and a bilateral inter-tripping protection system. The bilateral inter-tripping device is provided with a first switching input end, a second switching input end, a first group of digital quantity input end, a first group of digital quantity output end, a first group of optical fiber interface, a second group of digital quantity input end, a second group of digital quantity output end and a second group of optical fiber interface. In the bilateral inter-tripping protection system, the bilateral inter-tripping device is arranged on each corresponding traction substation. An optical fiber communication loop for a fault detection result is built between second feeders and first feeders of two adjacent substations, bilateral inter-tripping of the traction substation is achieved, so that fault information of the two feeders in an arbitrary contact network area can be reliably exchanged no matter when the traction substation in a contact network is in a normal running state or in a handover running state, and the bilateral inter-tripping protection reliability of a DC traction power supply system is improved.