The invention discloses a safety fool-proof device for workpiece processing of a numerical control machine tool, which comprises a mounting plate and mounting holes arranged on four sides of the mounting plate, support frames are symmetrically installed on the other two sides of the mounting plate, and one side of the support frame is evenly provided with Sliding holes, the limit pins are interspersed in the sliding holes, one end of the limit pins in the support frame is equipped with a pressure plate, the other side of the support frame is equipped with a fixing plate, and the positions of the fixing plates corresponding to each sliding hole are provided with wires. Hole, the screw hole is threadedly connected to the lead screw, and one end of the lead screw is provided with a rotary plate. By disassembling the fixing plate, it is convenient to replace the spring. Through the anti-fooling limit of the limit pin, the plate-shaped workpiece can only be placed corresponding to the fixed limit pin distance on the left and right sides, so that the plate-shaped workpiece can be stably contacted with the mounting plate. Only one adjustment is needed, and there is no need to re-set the tool, which is safer And high efficiency, good anti-fooling effect, solves the problem in the prior art that there is no anti-fooling effect for clamping plate-shaped workpieces.