Based on low degree of automation and poor reliability of existing air compressor control system, design scheme of mine air compressor on the basis of PLC variable frequency control was proposed with S7-300 programmable controller produced by America Siemens and MM440 frequency converter as core. Through combination of multiple functional modules, this scheme solved problems of low automation and poor reliability and achieved real-time monitoring of pressure temperature and current parameters. At same time, continuity of air compressor usage was ensured, human costs and waste of resources were reduced, which had high promotion value in coal mine production activities.