The structure and technological process of two sets 50 000 m3/h purification system of air separation unit in Shenhua Coal to Liquid and Chemical Corporation Ltd.,the automatic switch control logic of the valve,the sequence control automatic/manual operation and the process of program execution of molecular sieve purification system were introduced.According to the production operation, the sequence configuration program of molecular sieve adsorber was optimized.The molecular sieve sequence control logic alarm is simple and practical ,the efficiency and quality of the process operator can be improved.