Axial flux permanent magnet synchronous motor(AFPM) has small axial volume, high output torque and excellent reliability. In this paper, a new design scheme for the collaborative robotic joint is proposed with it. Due to the narrow installation space of the motor, the Halbach array with 90° magnetizing angle is selected to enhance the air-gap magnetic field magnetism. However, the waveform of the air-gap magnetic field is not well sinusoidal because of large harmonic content while the NdFeB permanent magnet material is expensive. To solve above problems, a special Halbach structure combining ferrite and NdFeB permanent magnets is introduced. Three kinds of permanent magnet combination structures are given, and the optimal combination is determined by three-dimensional finite element method which establishes the motor model. The results show that the designed coreless axial flux joint motor has high power density and compact structure The results show that the designed articulated motor has high power density and compact structure. In addition, after comparison with the basic permanent magnet structure motor, the permanent magnet combination Halbach can effectively reduce the motor cost and strengthen the motor stability.