A 
position sensor-free double closed-loop speed regulation control method for a brushless 
DC motor comprises the following steps: (1) initializing functional modules and peripherals; (2) opening AD (Analog-Digital) interruption and protection interruption; (3) detecting the start key of the motor, judging whether to start the motor, if yes, executing the next step, and if not, continuing to execute the step; (4) starting 
voltage detection, judging whether the 
voltage of a main circuit is larger than starting 
voltage, if yes, executing the next step, and if not, returning to the step (3); (5) entering a motor starting subprogram and beginning operating the motor; (6) entering a double closed-loop speed regulation subprogram, and regulating the rotational speed and the current of the motor according to voltage value; and (7) detecting a motor 
brake key, judging whether to press the key, if yes, entering a motor 
brake subprogram, and if not, returning to the step (3). The method provided by the invention overcomes the defects of larger size, low rotational 
speed accuracy and the like of the conventional 
motor controller, can accurately control different rotational speeds of the motor, and can simultaneously realize 
counter electromotive force zero-cross comparison 
position sensor-free reversing and Hall position 
signal reversing.