Abstract: The pressure swing adsorption (PSA) technique to produce high purity oxygen is researched by using a zeolite molecular sieve column and a carbon sieve column. A control system based on PLC is designed to regulate the flow and pressure, as well as to control the solenoid valves, with the advantages of high adaptability and reliability. The technical process of two adsorption stages is selected, the optimum adsorption time of every column is determined and the effect of air displacement on oxygen purity in the carbon molecular sieve column is analyzed. The experimental results show that the highest oxygen purity can be up to 99.5%.