The key to the realization of direct torque control method for brushless DC motor with open winding is the selection of voltage vector, in which the analysis of different voltage vector characteristics and the establishment of the optimal voltage vector selection table have a crucial influence on the motor performance. In this paper, the characteristics of different voltage vectors under the direct torque control method of brushless DC motor with open winding are analyzed in detail, and the motor state under the action of different vectors is analyzed and different voltage vector selection tables are established. The results show that when the large vector is selected as the positive voltage vector and the large vector, medium vector, small vector and zero vector are respectively used as the zero-voltage vector, the two-phase conduction mode in the three-phase six state of OW-BLDCM can be satisfied. The simulation results verify the correctness of the theoretical analysis. The motor torque ripple is approximate and large when the large and middle vector act as the zero voltage vector, and approximate and small when the small and zero vector act as the zero-voltage vector. The motor performance is better when the small vector acts as the zero-voltage vector.