An electric motor includes electric motor stator and a rotor rotatably inserted in the electric motor stator. The electric motor stator includes a stator iron core and an end cap. The end cap is formed, in an interior thereof, with a receiving space that receives the stator iron core therein. The stator iron core includes an annular stator yoke and a plurality of stator teeth extending radially from an internal circumferential surface of the stator yoke. The stator yoke has an external circumferential surface that is recessed to form positioning grooves. The end cap has an internal surface that is protruded to form positioning posts that are respectively insertable into and connectable with the positioning grooves. The positioning grooves respectively correspond to the stator teeth in a radial direction of the stator iron core.