The invention relates to a fixing device, in particular to a fixing device of an electric transmission line damper. The fixing device comprises a square supporting plate and a cylinder-shaped supporting rod, the two sides of the rear side face of the square support plate are each provided with one clamping hook, the two sides of the front side face of the square support plate are each provided with one connecting rod, the other end of each connecting rod penetrates through the cylinder-shaped supporting rod, a thread is arranged on the outer surface of the tail end of each connecting rod, and the positions, on the two sides of the cylinder-shaped supporting rod, of each connecting rod are each in threaded connection with one fastening nut. One operating handle is rotationally connected with the middle of the cylinder-shaped supporting rod, a clamping groove is formed in one end of the operating handle, one connecting column is arranged in the clamping groove, a connecting base is rotationally connected with the rotary column, and the connecting base is connected with a fixed hook. By means of the fixing device of the electric transmission line damper, an existing damper is prevented from sliding and falling off, the damper is firmly fixed, and the operation is convenient.