The invention relates to a feeding and clamping mechanism provided with an air cylinder. The mechanism comprises the air cylinder, a carrier roller, a feeding machine body, a screw nut and an adjustable nut; a material is placed at the upper end of the carrier roller; two ends of the carrier roller are connected with the feeding machine body; a guide rail is fixedly arranged on the outer side of the feeding machine body and is connected with a feeding platform through a guide rail groove; the screw nut is fixedly arranged on a bottom plate of the sliding feeding platform; the adjustable nut is arranged at the upper end of one side of the sliding feeding platform; fixed tongs are arranged at one end of the adjustable nut; the air cylinder is arranged on the side, far away from the fixed tongs, of the sliding feeding platform; and movable tongs are arranged at the end, close to the feeding machine body, of the air cylinder. The mechanism has the beneficial effects as follows: the mechanism is simple in structure and convenient to operate, the freedom degree of the material is controlled, a certain effect on fixing the material is realized, and the working efficiency is improved.