Abstract: In allusion to the higher interstage temperature and variable pressure for SAFE compressor sets in CNG station, a technical analysis on the problems is made.The analysis results show that damage of secondary air inlet valve and leakage of secondary air bleeding valve are major causes.Technical modifica-tion program for the secondary air inlet valve is presented.For issues about water overflow from top water container of cooling system.technical reform methods in repairing heat exchanger and enhancing sealing are proposed.