The invention discloses a blade of a rotary electric shaver. The blade comprises an annular cutterhead and a connection seat fixedly connected to the middle part of the cutterhead, wherein multiple cutter bodies are arranged on the upper end surface of the cutterhead; a cutting surface is arrange at the tail end of each cutter body; cutting edges are formed at positions, which are located at the tip parts of the cutter bodies, on the cutting surfaces; the cutter bodies and the cutterhead are formed by carrying out integration molding on a ceramic material; and the connection seat is molded at the middle part of the cutterhead from plastic. According to the blade of the rotary electric shaver, the connection seat is directly molded at the middle part of the cutterhead from the plastic, so that the connection seat and the cutterhead are connected more tightly; during falling test of the blade, as the integrality of the cutterhead and the connection seat, no internal stress is generated; and therefore, no cracks are formed on the cutterhead or the cutterhead cannot be broken into pieces, and the safety of the blade is improved. The invention further discloses a machining method of the blade of the rotary electric shaver. The machining method comprises the steps of cutterhead forming, grinding and injection molding of the connection seat. The blade machined through the machining method is high in blade strength, breakage-resistant and not liable to break.