Abstract: Parts of mine have achieved certain energy-saving effect at the moment by adjusting the frequency and speed of main fan to match the ventilation network.However，it does not regulate speed for energy-saving according to the actual production time of each mine.The control of underground main fan speed and air output is introduced with LOGO time-sharing and frequency conversion，so as to save energy by controlling fan speed matching the underground production time in the pit.

Key words: The main fan frequency conversion, LOGO time-sharing adjusting speed, Energy saving