The utility model discloses a small blade inner cambered surface abrasive belt grinding device. A contact rod (9) is arranged between a first transition wheel (6) and a second transition wheel (7), a sponge grinding head (10) is arranged at the front end of the contact rod (9), a motor (2) is arranged on the rear side of a lathe body (1), the motor (2) is mounted on a vertical plate (8), a driving wheel (3) is sleeved on an output shaft of the motor (2), and the driving wheel (3) is connected with the first transition wheel (6), the second transition wheel (7) and the sponge grinding head (10) through an abrasive belt (4). According to the small blade inner cambered surface abrasive belt grinding device, sponge materials are used as the grinding head, the diameter of the grinding head is enabled to be smaller than 10 mm, the problem that a small blade of a gas compressor is hard to grind because the inner camber surface curvature radius of the small blade is small is effectively solved, a grinding belt is arranged between the sponge grinding head and the abrasive belt and used as a middle material of the sponge grinding head and the abrasive belt, the grinding belt can be abraded replacing the sponge grinding head, and therefore the service life of the sponge grinding head is greatly prolonged.