A railway signal cable grounding system, comprising a railway signal cable (10), a through ground wire (20) and surge protection devices (30), the number thereof is equal to the number of segments of the railway signal cable. One end of an outer metal cable sheath (11) of each segment of the railway signal cable is directly connected to the through ground wire and the other end of the outer metal cable sheath is connected to the through ground wire via a surge protection device. Under the power frequency condition, the minimum traction current, that can be neglected, passes through one end of the outer metal cable sheath since the surge protection device is in a high-impedance near open-circuit mode state, so that the risk of burnout of the cable is avoided. Under the lightning transient condition, one end, connected to the through ground wire via the surge protection device, of the outer metal cable sheath enables the potential of the outer metal cable sheath at the end to be reduced to below a protection voltage of the surge protection device, and the cable and an apparatus are not damaged by the protection voltage, so that safe operation of the cable and the apparatus in a lightning environment is ensured.
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