Thick bedrock working face is prone to produce the phenomenon of large overhanging area of the arc-shaped triangle at the end of the working face during the mining period, which is prone to produce the accident of large-area coming pressure on the roof plate and affects the safe production of coal mines. In order to analyze the mechanism and evolution law of the formation of the arc-shaped triangle at the end of the working face, we take the working face of 12407 of Huangyuichuan Coal Mine as the research background and focus on the problem of large overhanging area of the arc-shaped triangle at the end of the working face during the mining process in the gum transporting and wind-returning chutes, through the combination of theoretical analysis, laboratory test and numerical simulation. In order to solve the problem of large overhanging roof area in the working face of 12407 working face, through theoretical analysis, laboratory test and numerical simulation, we analyzed the formation mechanism of 12407 working face arc triangle, studied the evolution law of 12407 working face arc triangle in the process of mining, and put forward the management plan of large overhanging roof area in 12407 working face arc triangle of Huangyuchuan Coal Mine. Research results show that: due to the roof plate "O-X" broken, the roof plate rock strength is larger, the working face two ends of the location of the hard roof plate is difficult to collapse, easy to produce the working face roof end of a large area of overhanging, the formation of the end of the arc-shaped triangle, theoretical calculations of the Huangyuchuan coal mine 12407 working face end of the arc-shaped triangle Theoretical calculation shows that the overhanging distance of the triangle is 20.1m; by analyzing the damage characteristics of the roof plate in the air-mining area during the advancement of the working face, it is concluded that with the advancement of the working face, the geometrical form of the working face's end arc-shaped triangle is gradually reduced, but the magnitude of the reduction is relatively small, and there is still a safety hazard of the end-end large-scale overhanging roof, and the Huangyu-Chuan coal mine 12407 working face's end-end arc-shaped triangle management plan is proposed to manage the overhanging roof in the field. Along the parallel direction of the working face from the original 20m reduced to 5.3m, along the vertical direction of the working face from the original 15m reduced to 6m.