In view of the inaccurate commutation of brushless DC motors in highspeed state, a novel method of sensorless control is proposed based on the special relationship between the motor back electromotive force (EMF) and the commutation points. The novel method can calculate the commutation point accurately. The uncertainty of the phase delay estimation process in traditional algorithm is avoided, and the dynamic response performance of the sensorless control algorithm is improved. A look\|up table method is introduced to execute the algorithm, and the implementation of the algorithm is simplified. A new type of motor phase voltage detection circuit is involved, which simplifies the external circuit of the sensorless control algorithm, and makes the implementation cost of sensorless control algorithm further decreased. Experimental results show that the circuit can effectively detect the phase voltage of the motor. The proposed algorithm is simple to implement and has great advantages in dynamic response.