Abstract: A model of process in PTA oxidation reaction system closely related to air compressor group was set up using the Aspen Plus platform. The sensitivity of several key process parameters of the air compressor and gas expander was analyzed, and the influences of air compressor stage pressure ratio, air compressor first stage inlet temperature, gas expander first and second stage inlet temperatures on their powers were studied. The optimal process parameters were obtained which can reduce the air compressor power requirement and improve the gas expander output power. The results provided a theoretical basis for the energy saving reconstruction.