Coal mining in China is mostly underground, and underground operations must be carried out under good ventilation. Contra-rotating axial flow fan is one of the commonly used ventilation equipment in coal mine, but there are some problems such as low efficiency and large energy consumption in the actual use of contra-rotating axial flow fan in Boli Coal Mine. In order to solve this problem, according to its working characteristics, it is decided to adopt the principle of frequency conversion speed regulation to adjust the frequency of the driving motor of the fan, so as to realize the optimal flow matching of the two-stage moving blade interference speed regulation of the fan, so as to achieve the purpose of real-time adjustment of the working condition of the fan, meet the demand of mine air volume and negative pressure, reduce the full load operation of the fan, and achieve the energy saving effect.