Abstract: Halbach arrays permanent-magnet（HAPM）motors are appropriate for high-precision servo system in consideration of their outstanding torque output performance.The key in design and optimization to ensure excellent performance of the HAPM motors is that how to predict the internal magnetic fields distribution accurately. The analytical sub-domains of stator slots are divided into slot-openings and slots. As a consequence, a two-dimensional exact analytical method fits HAPM motors with semi-closed slots is proposed,for predicting their air-gap magnetic fields, cogging torque,output torque, flux linkage, back electromotive force（back-EMF） and the armature winding inductances. Results from this analytical method are compatible with corresponding finite element analysis（FEA）, and the back-EMF waveform of them is basically in accordance with that of experiment, which supports the reasonability of the proposed analytical model.