The bidirectional impeller pump is a kind of double impeller pump driven by single motor, which can pump and drain water with a single pump. This design effectively overcomes the disadvantages of complicated pipeline arrangement and poor reliability caused by multi-pump operation. In this paper, a bidirectional impeller pump is designed, which can realize the two-way flow of fluid through a special flow channel topology, and the structure and electromagnetic design of the core drive component of the permanent magnet brushless DC motor are carried out. The magnetic field numerical model of the motor is established by Maxwell, and the distribution characteristics of the air gap magnetic field and electromagnetic output characteristics are simulated and analyzed. Taking the output power and efficiency as the optimization objectives, the motor parameters such as the number of turns and wire diameter are optimized. The prototype and the experimental platform for the output characteristics of the bidirectional pump are designed and processed. The simulation results and the rationality of the structure are verified through experiments.