Abstract: CNC drilling machine is one of the indispensable and important equipment in the field of modern machining, and its processing accuracy and intelligent level are directly related to the product quality and production efficiency. Aiming at the problems of low machining precision and low intelligence level of CNC drilling machine, a control system of CNC drilling machine based on PLC is designed. The control system is based on Omron PLC controller and adopts semi-closed loop servo control scheme to control X axis, Y axis and Z axis servo motor. The input data is directly imported into the PLC controller in BIN format to achieve automatic detection and remote control. The experimental conditions of CNC drilling machine control system are constructed and verified. The verification results show that the machining accuracy of the designed CNC drilling machine control system is less than 0.01mm, which improves the intelligent level of the drilling machine and helps to improve the product quality and production efficiency of the drilling machine.