The invention provides a grounding wire clamp. The grounding wire clamp comprises a box body, wherein an X-shaped clamping plate is arranged in the box body and comprises a left clamping plate and a right clamping plate, a first pin shaft is arranged at a cross position of the left clamping plate and the right clamping plate in a penetrating way, a first reset spring is arranged on the first pin shaft, a transmission piece is arranged at an upper part of the X-shaped clamping plate, a right side of the bottom of the transmission piece is connected with an upper end of the left clamping plate in a sliding way, a left side of the bottom of the transmission piece is connected with an upper end of the right clamping plate in a sliding way, a first through hole is formed in the transmission piece, a screw rod is arranged in the first through hole and is in threaded connection with the box body, an upper end of the screw rod is fixedly arranged on the box body and is connected with an uppershaft of a motor, the transmission piece is driven to upwards and downwards move by the screw rod so that opening and closing of the left clamping plate and the right clamping plate are achieved. Thegrounding wire clamp provided by the invention has a three-level force increasing effect of gear pair threaded pair lever, a motor with a holding function is not needed to be used, and the motor capacity, the cost and the power loss are all reduced; and moreover, the clamping process is stable, and the impact to a wire is also greatly reduced.