The invention belongs to the field of automobile accessory machining, and particularly discloses a drilling and tapping clamp. The clamp comprises a base; a slide way is arranged on the base; a firstfixing block and a second fixing block are arranged on the base; conical surface steps matched wit a part to be machined in side contour are arranged on the two fixing blocks; the first fixing block is fixedly arranged on the base; the second fixing block is connected to a sliding channel of the base in a sliding mode; an air bag is arranged between the two fixing blocks; the two ends of the air bag communicate with air pipes separately; valves are arranged at the communication positions of the air pipes and the air bag; the air pipes communicate with air cylinders; wedge-shaped blocks are connected to the output ends of the air cylinders, and each wedge-shaped block has a conical surface radian matched with the radian of the part to be machined. The clamp can be widely applied to machining the part which cannot be positioned easily due to a certain radian on the upper surface and the lower surface. Compared with the prior art, the clamp has the advantages that the workpiece with a certain radian can be accurately positioned, chippings generated in the tapping process can be automatically cleared, and therefore subsequent clearing of the chippings on the part to be machined can beavoided.