The utility model discloses an additional anchor device for a steel strand wedge-type anchorage and a tensioning tool for mounting an anchor device. The additional anchor device comprises a secondary anchor and a reset ring plate which is arranged between a primary common anchor and the secondary anchor. The primary common anchor is the anchor device set and used for fixing the steel strand. Resetting holes are formed in the reset ring plate and equal to anchor holes in a primary anchor ring in number. The secondary anchor comprises a secondary anchor ring and a secondary anchor clamping piece. A groove is formed in the upper bottom face of the secondary anchor ring and internally axially provided with secondary anchor holes equal to the anchor holes of the primary anchor ring in the number. A second clamping piece hole is formed in the secondary anchor clamping piece along the central axis. Tooth-formed zigzags are formed on the inner wall of the second clamping piece hole. The secondary anchor clamping piece is divided into two parts along the axial direction. According to the arrangement, reinforcement of the common wedge-type anchor is achieved; even under equal load action of the vehicles, a rigid suspender of a tied-arc bridge is effectively protected from slipping; the secondary anchor ring is added as a second defensive line of the steel strand wedge-type anchorage of the rigid suspender.