Gongming ultra-deep shaft is a vertical shaft for the water transmission line of Luotian-Tiegang Reservoir. Its foundation pit floor is about 70m higher than the groundwater level, and the anti-flat problem is significant. Based on Gongming ultra-deep shaft, three-dimensional numerical simulation is used to study the force characteristics of anti-flat anchor reinforcement pile on the ultra-deep shaft floor and the optimization of pile distribution parameters. It is found that the closer the anchorage reinforcement pile is to the center of the floor, the more it plays the drawing function first, and the greater the maximum axial force is. As the anchorage reinforcement pile is far away from the center of the floor, the maximum axial force decreases gradually. The anchor reinforcement pile in the central part of the bottom plate first plays the role of drawing and at the same time makes the bedrock uplift. The peripheral anchor reinforcement pile is significantly affected by the bedrock uplift, and even appears the lateral friction resistance on the pile side, which is manifested as the axial force decreases sharply, the shear stress on the pile side decreases, and the effective anchorage depth increases. According to the simulation results, the 7th and 8th ring anchor reinforcement piles in the original scheme can be combined into one ring anchor reinforcement piles. After optimization, the maximum axial force value of anchor reinforcement piles increases by about 9% , which is lower than the design value of tensile capacity, and the water buoyancy force shared by anchor reinforcement piles decreases by about 4% , but the number of anti-buoyancy anchor reinforcement piles is saved by about 23% , which meets the engineering safety requirements and has significant economic benefits.