The invention relates to a connection device for a folding column, a segmented insulator and a current transformer. A connection device is connected between two adjacent insulator segments of the segmented insulator, the connection device includes a first connector and a second connector for connecting the corresponding insulator segments, and a middle connection piece connected between the firstconnector and the second connector, the middle connection piece is a hollow column, the first connector and the second connector are internally provided with an optical fiber through hole, the hollowcolumn is coaxially arranged with the first connector and the second connector, and two ends of the hollow column are connected with the first connector and the second connector through hinged structures. The connection device also comprises a detachable fixing structure for preventing the first connector and the second connector from rotation. The optical fiber through holes of the first connector and the second connector and the internal of the hollow column form an optical fiber channel for passing of the optical fiber. By using the connection device of the present invention, the technicalproblem that the optical fiber is easily damaged during folding and transportation of the insulator in the prior art is solved.