The invention discloses a clamping device with a ratchet device for a ground wire. The clamping device comprises a chuck, a propelling post, a clamping piece, a connection frame, an insulating rod and a ratchet fastening device, wherein the chuck comprises an upper bump, a lower bump and a connection block; the upper bump and the lower bump are arranged in parallel and are fixed at two ends of the connection block separately to form a structure with a groove; the propelling post passes through the lower bump and is in threaded connection with the lower bump; the clamping piece is fixed at one end, entering the inside of the groove, of the propelling post; a fixture block is arranged at one end, outside the chuck, of the propelling post and is a polygon; the ratchet fastening device is hinged with the connection frame; the connection frame is fixedly connected with the insulating rod; the ratchet fastening device comprises a fixture block mating hole; and the fixture block mating hole is in fit connection with the fixture block. By adopting the ratchet device, the target that the propelling post can only rotate in the same hour hand direction and cannot rotate in the other hour hand direction in the swing process of the insulating rod can be achieved, so that the single tightening or disassembling process can be continuously achieved through only one-step installation.