The invention discloses a clamping device with a self-locking structure. The clamping device comprises a support base, a strip-shaped guide rail is fixed to the top face of the support base, a clamping structure is arranged on the support base and comprises a clamping frame, a vertical guide rail protruding block is integrally formed on the clamping frame, a frame body is arranged on the clampingframe, guiding sliding blocks are fixed to the symmetric inner walls of the frame body correspondingly, a clamping plate is arranged on the frame body, guiding circular rings are fixed to the symmetric side walls of the top face of the frame body, two guiding column rods are fixed to the back face of the clamping plate, a telescopic air cylinder is fixed between the middle of the top face of the frame body and the middle of the back face of the clamping plate, a cavity is formed in the clamping-pressing face of the clamping plate, an abutting-pressing plate is arranged in the cavity, a reset spring is fixed between the abutting-pressing plate and the side wall of the cavity, a self-locking support rod is fixed to the back face of the clamping plate, and a self-locking warping rod is further arranged. The clamping device is reasonable in structure arrangement, stability and reliability of clamping can be ensured through self locking, workpieces are not prone to being damaged, applicability is high, and practicality is good.