The invention relates to a method and device for generating mechanical reciprocating bistable-state motion by virtue of electromagnetism. The method is characterized by comprising the following steps: jointing two identical permanent magnets symmetrically on a motion component; placing the parts, adhered to the permanent magnets, of the motion component between two magnetic pole air gaps of an alternating magnetic field; sucking, shutting and repelling the permanent magnets on the motion component repeatedly by virtue of two magnetic poles by the alternating magnetic field so as to drive the motion component to perform reciprocating motion; and regulating the position and structure between the motion component and the two magnetic poles of the alternating magnetic field, thus the motion component can be enabled to perform reciprocating swing and reciprocating linear motion. The invention also provides the device for generating mechanical reciprocating bistable motion by virtue of electromagnetism; through exciting or rotating the permanent magnets by an alternating power source, the alternating magnetic filed is formed on a soft magnet; and the parts, to which the permanent magnets are attached, of a swinging rod and a pushing rod are placed in the magnetic air gaps of the soft magnet. According to the invention, the characteristics of the permanent magnets that the permanent magnets are stressed in the alternating magnetic field and the permanent magnetic tends to be stable once being sucked with the magnetic poles of the alternating magnetic field are utilized, the structure of the device is simplified, and the state is maintained to be stable without energy consumption.