In view of the realization of the control of high-speed positionless brushless DC motor, aiming at the flaw of inaccurate commutation in high-speed state, and based on the working principle and mathematical model of Brushless DC motor, the traditional back EMF zero crossing method and current and speed double closed-loop PID control are used to phase the commutation signal with the detected phase difference of single-phase voltage and single-phase current as commutation error. Finally, the simulation experiment is carried out by using Matlab / Simulink. The simulation results show that the running speed of the control system can reach as high as 1×105 r/min. After compensation, the commutation signal can make the speed reach the given reference speed faster, and the commutation signal after compensation can make the speed reach the given reference speed faster with a smaller required current. Meanwhile, the operation is relatively stable in the case of sudden change of torque and speed.