An ultrasonic cutter head comprises a cutter head end portion (1), a cutter shaft (2), and a cutter body (3). One end of the cutter shaft (2) is connected to the cutter head end portion (1), the other end of the cutter shaft (2) is connected to the cutter body (3). A main body of the cutter head end portion (1) has a flat structure. An upper surface and a lower surface of the flat structure form an upper cutter edge (11) and a lower cutter edge (12) of the cutter head end portion (1), respectively. A protruding portion (14) is formed at a front end of the upper cutter edge (11). The upper cutter edge (11) has a thickness exceeding that of the lower cutter edge (12). The protruding part is smooth and free of edges.
