Robot joint motors have higher requirements for the motor′s overload capacity, motor weight and response speed. However, the traditional torque motor has larger rotor outer diameter, rotor mass and moment of inertia, and thus slower response. Based on the Halbach array, a joint motor for robots is designed. The magnetic shielding effect of the Halbach array is utilized, and non-magnetic aluminum alloy is used as the material of the rotor yoke, so as to reduce the mass and moment of inertia of the rotor and improve the response speed of the motor. The advantages of Halbach array are analyzed. Several common Halbach array structures are listed. The size parameters of the motor are determined. The influence of the size of the magnetic steel based on the Halbach array on the performance of the motor is analyzed by the electromagnetic field finite element simulation. Finally, the effectiveness of the technology is verified by experiments.