The utility model discloses a connecting and clamping device for a steel tube tower, comprising a rear cap area, a middle body and a screw thread area, wherein a center shaft of the rear cap area and the middle body is provided with a hole; the outer surface of the middle area is adaptive to the inner surface of a flange plate of the steel tower in shape; the screw thread area is movably connected with a mold; and the screw thread area is a part of a bolt passing through the hole of the center shaft of the rear cap area and the middle body. In the utility model, the integrated rear cap area, the middle body and the screw thread area are divided into two parts which are movably connected, one part comprises the rear cap area which is not easily damaged and the middle body, and the other part comprises the screw thread area which is easily damaged and needs to be replaced, so that the function of the original clamping device still can be realized when the lengthened bolt passes through the holes of the clamping device and the mold.