An in-depth study was conducted on issues such as the determination of the basic roof fracture step distance, the structural form of the basic roof and the reasonable working resistance of the supports in the main face of a certain deep coal mine in Kailuan. The calculation formula for the basic roof fracture step distance was derived, a judgment method for the structural form of the basic roof in the main face was established, and the calculation formula for the working resistance of the supports under different structural forms of the basic roof was constructed. The results show that the initial fracture step distance of the roof of the working face is 26.7 m, and the periodic fracture step distance is 15.5 m. When the mining height is less than 4.52 m, the basic roof is prone to form a "masonry beam" structure, and when the mining height is greater than 4.52 m, the basic roof will enter the collapse zone in the form of a "cantilever beam". The influence of the fracture step distance of the basic roof and the support control distance on the working resistance of the supports under the two structural forms was analyzed, and it was determined that the reasonable working resistance of the supports in the 46092 working face should not be less than 10 851 kN. The rated working resistance of the existing supports is 10 000 kN, which is slightly insufficient in some areas of the working face.