The invention discloses a clamping device used for fixing a bent tube pipeline. A bent tube slot which penetrates through the upper surface and the side surface of a clamping plate is formed in a fixed plate of the clamping plate; the bent tube slot is formed by splicing a U-shaped slot formed in the inner surface of the fixed plate and a U-shaped slot formed in the inner surface of a movable plate; a positioning hole is formed in the fixed plate; U-shaped steel plates which are integrated with a clamping handle mutually are blocked into the U-shaped slots; two gaskets fixedly arranged on theinner side of each U-shaped steel plate are fixedly arranged on the fixed plate through the U-shaped slots; the positioning hole passes through the relatively wide side surface of the fixed plate, andpasses through relatively great side surfaces of at least two transverse connecting plates; and arc-shaped concave surfaces are formed in the end surfaces, matched with the gaskets, of the movable plate. The clamping device is simple in structure, is convenient to operate, is safe, can achieve clamping through one step, is relatively low in cost, and is more durable in use in comparison with a conventional all-wood test tube. By replacing the gaskets in mould slots and replacing gaskets of different thicknesses, bent tubes of various dimensions can be processed, so that scope of application is further expanded.