In order to meet the requirements of clinical delivery and solve the shortcomings of traditional forceps and manual aspirator, a closed-loop PID controlled electronically-controlled vacuum extractor was developed and designed. The ATmega128L microcomputer processes the negative pressure information fed back by the negative pressure sensor through the PID control algorithm processing negative pressure sensor feedback negative pressure information to output signals to control the frequency converter, and then controls the vacuum extractor to carry out accurate control of the negative pressure. At the same time, the system also has real-time screen negative pressure information display, emergency one-button release of negative pressure, negative pressure abnormal sound-light alarm and other functions, which enables medical staff to operate more confidently and efficiently. The test compared start-stop control that the commonly used in the market with the PID control algorithm which used in this system. Result showed that the PID control algorithm was more accurate and efficient; In the repeatability experiment, the target values of -40kPa, -50kPa and -60kPa were respectively tested, and the mean values of the test were -40.21±0.66kPa, -49.67±0.87kPa and -60.57±1.24kPa. Results showed that the system had a good stability and could meet the needs of clinical midwifes.