The prior art cutter head design a continuous welding tooth in a single direction on the base of the hole saw, cutting wood is sharp but there is no left and right top surface oblique tooth inclination angle and tooth top surface step design. When encountering hard metal such as iron nails in the wood, The cutting edge with a single-sided sharp design is prone to chipping, damaging the sharpness of the edge of the alloy cutting head, resulting in the inability to continue cutting wood and obtaining a smooth wood cutting surface. Due to the single-sided cutting, the amount of wood cut is small, resulting in a general cutting speed. At the same time, when cutting very hard wood, the cut cylindrical wood block is easy to get stuck in the body of the hole saw tube and is not easy to take out. It has no left-right staggered and tooth top surface step design. During use and wear, the sharpness will gradually decrease, and there is no secondary opening sharp cutting performance. As shown in Figure 2, the prior art cutter head design 2 is suitable for cutting thin metal plates and other materials. The shape of the cutter head has no side bevel and no rounding at the bottom. When used to cut wood, it is easy to cause wood chip removal Smooth, easy to block the sawing path, the wood cutting cross section is rough and large in texture. The step difference of the stepped part of the top surface of the cutter head is not toothed. During use and wear, the sharpness will gradually decrease, and there is no secondary opening sharp cutting performance. The inclination angle of the cutter head is not large, which results in a large resistance during the cutting process. When cutting wood and internal nails, the speed will be significantly slowed down. Although the design of the cutter head is less likely to collapse than the previous cutter head, the cutting speed is significantly slower. And there is a sense of frustration during the cutting process.