Abstract: In view of problem that most of existing oxygen supply systems of refuge chamber applied multistage protection system, and oxygen supply subsystems are independent of each other and cannot automatically switch among them, which causes the oxygen supply unstable, an automatic oxygen supply system of refuge chamber based on PLC and PID monitoring technology was designed. The system integrates multistage oxygen supply systems and environment parameters monitoring system through loop optical fiber system. Based on the detected environment parameters in real-time, and uses PLC and PID monitoring technology, the system can realize intelligent adjustment between all levels of oxygen supply system and automatic continuous supply oxygen of underground refuge chamber, and can automatically switch to the next level of oxygen supply system when a certain level of oxygen supply system happens failure, which improves stability and safety of the oxygen supply of refuge chamber. The site test results verify reliability of the system.