Stretching method and device of prestressed anchor cable

The invention relates to the technical field of construction by prestressed anchor cables and discloses a stretching method and device of a prestressed anchor cable. The stretching method comprises the following steps: placing an anchor padding plate between an upper padding plate and an anchor device; clamping the prestressed anchor cable with an elastic clamping piece, placing the elastic clamping piece in the anchor padding plate and reserving a gap between the upper surface of the elastic clamping piece and the upper padding plate; performing the first stretching to the prestressed anchor cable and enabling the stretching value of the prestressed anchor cable to reach a designed stretching value; propping the upper padding plate against the upper end of the elastic clamping piece and performing the second stretching to the prestressed anchor cable. According to the method, the prestressed anchor cable is stretched twice; in the process of the first stretching, the gap is reserved between the upper padding plate and the elastic clamping piece, so that the phenomenon that the prestressed anchor cable is locked by the elastic clamping piece in the stretching process is avoided, thus avoiding the failure of the prestressed anchor cable; in the process of the second stretching, the upper padding plate is directly propped against the elastic clamping piece and the prestressed anchor cable can be locked by the prestressed anchor cable so as to complete the stretching of the prestressed anchor cable and ensure that the stretching value of the prestressed anchor cable can meet requirements.