Abstract：In view of the difficulty of soft mining of large dip angle coal seam in Yimen Coal Mine, the technical parameters of hydraulic support, shearer and conveyor in working face are calculated by analyzing the mining characteristics of steeply inclined unstable extra-thick coal seam, and the ' three machines ' equipment in working face is selected and applied in engineering. The results show that the horizontal section working face of Yimen Coal Mine should choose the top coal caving hydraulic support with flexible, lightweight and good sealing performance, short fuselage shearer and conveyor matching with mining and caving capacity. It is calculated that the working resistance of the support is not less than 1920 kN, the actual power of the shearer should be 94 ~ 109 kW, the transportation capacity of the front scraper conveyor should not be less than 300 t / h, and the rear conveyor should not be less than 952 t / h. The ' three machines ' selection results of the working face were applied to the 1212 working face of Yimen Coal Mine. During the field observation period, the operating rate of the shearer reached 60 %, and the working resistance of the support met the roof control requirements. The shearer cut coal and top coal caving process worked in parallel, achieving high yield and high efficiency.