Abstract: Instrument compressed air is used as the power source of pneumatic actuator or the purge gas of precision instrument in power plant.It plays a significant role in the economic and safe operation of power plant. The compressed air dryer filters and dries the outlet of the air compressor which ensuring the purity of the compressed air. This paper discusses the problems existing in the program control logic during the commissioning of the compressed air dryer in a power plant. Through the renovation of the control system for the instrument compressed air dryer, a programmable optimization logic for the compressed air dryer is proposed, and can be used as reference in equipment application of compressed air dryer.