Energy saving principles of fan frequency conversion speed regulation in coal mine were described, as well as frequency converter, PLC selection and design of variable frequency speed regulation system, etc. Variable frequency speed regulation scheme of fan was put forward. The result showed that variable frequency speed regulation technology could save 56 thousand yuan per month for the mine with remarkable energy saving and consumption reduction. At the same time, this technology could be used in transportation and drainage system, which could improve intelligent level of mine and energy savings.