The invention relates to a closed-loop control system of a high-speed motor of a PCB drilling machine. The closed-loop control system comprises a high-speed motor connected with a power phase, a powerinverter connected with a power end of the high-speed motor and a velometer arranged on the high-speed motor and connected with the power inverter, wherein, the velometer sends detected and treated frequency signals of a rotor of the high-speed motor to the power inverter and conducts the closed-loop control of the rotating speed of the high-speed motor. As the closed-loop control system of the invention has high automation and can implement the continuous detection and the automatic adjustment to high-speed rotation and instantaneous velocity of the rotor, the processing quality and the normal operation of the PCB drilling machine can be effectively ensured.