The invention discloses a Halbach-structure-based iron-core-free axial 
magnetic field brushless direct-current electromotor which comprises a 
stator iron-core-free armature disc, a permanent 
magnet, a rotor disc, a shaft, a bearing and a rotor outer shell, wherein two symmetrical rotor discs are arranged at two sides of the 
stator iron-core-free armature disc; the 
stator iron-core-free armature disc and the rotor disc are installed on the shaft; the shaft is installed in the rotor outer shell through the bearing; the permanent 
magnet is pasted on the rotor disc, and is pasted on the inner surface of the rotor outer shell; a Halbach 
magnet structure with axial magnetizing and tangential magnetizing is adopted for the permanent magnet, and an enclosed 
magnetic circuit is formed automatically; and a soft magnetic material is placed at the middle of the permanent magnet with tangential magnetizing. According to the invention, on the basis that more permanent magnets are not used, flux density with great air clearance can be obtained, and are is in sine distribution; the output torque is high; the 
torque density is large; the efficiency is high; the structure is simple; the 
assembly is simple; and the Halbach-structure-based iron-core-free axial 
magnetic field brushless direct-current electromotor is suitable for relevant driving occasions with compact structures for electric automobile hub motors and the like.