The invention discloses a use method of a device for fixing an opposite-pull metal rod piece. The method includes the steps of matching a first wedge-shaped plane and a second wedge-shaped plane of a wedge-shaped block to form a right angle, attaching the right angle to the joint of the upper edge and the right-angle edge of a trapezoid hole, inserting a limiting pin into a pin hole after a metal rod piece clamping block is threaded, and bending the limiting pin at one side; pulling the end of the wedge-shaped block, provided with a square block, close to the metal rod piece clamping block after a metal rod piece to be fastened penetrates through a formwork, and making the metal rod piece to be fastened penetrate through the metal rod piece clamping block from a third through hole and a first through hole; keeping the wedge-shaped block in the vertical direction, and knocking at an end protrusion through a hammer, so that the wedge-shaped block moves downwards and the metal rod piece is fastened; knocking the end of the wedge-shaped block, provided with the square block, through the hammer when concrete reaches the collapsible die age, picking the device off the metal rod piece, and relieving fastening of the metal rod piece after the wedge-shaped block gets loose. The use method is high in construction speed, and the opposite-pull metal rod piece can be rapidly and firmly fixed.