The invention belongs to the technique of tool design and relates to a clamp used for positioning a rear-section piece during gluing assembly of a paddle. The clamp comprises a first bolt (1), an inverted-n-shaped body (2), a second bolt (3), a movable block (4) and a positioning pin (10). The inverted-n-shaped body (2) comprises an upper template (2-1) and a lower template (2-2). A threaded through hole (6) is formed in the left side of the inverted-n-shaped body (2). A rectangular groove (9) is formed by the upper template (2-1) and the lower template (2-2). Oval through holes (8) are formed in the positions, corresponding to the movable block (4), of the inverted-n-shaped body (2). The positioning pin (10) penetrates through a through hole (11) in the upper template (2-1) and a through hole (12) in the lower template (2-2). By the adoption of the clamp, the effect that the rear-section piece of the paddle is positioned rapidly when the rear-section piece is assembled to a girder can be guaranteed; and positioning is accurate, the assembly quality of the rear-section piece and the girder is guaranteed, and the non-qualified rate during assembly is decreased.