In order to solve the problem of huge water pressure on the up-arch during tunnel operation caused by the insufficiency of conventional drainage system in road tunnels, a new type of three-way drainage system was researched, and a reverse drain was designed in the center of the up-arch to carry out the drainage, meanwhile, the cavern will become the gathering place of water during flood season, and at this time, the tunnel will face huge water pressure, and the location of the cavern becomes one of the influencing factors, therefore, the influence of different spatial locations of the cavern on lining was investigated in the new type of three-way drainage system. Therefore, the influence of different cave space location on lining under the new three-way drainage system was investigated. Meanwhile, the pressure reduction performance of the new three-way drainage system with that of the conventional drainage system was compared. The results found that the three-way drainage system has significant pressure reduction performance, especially in the position of the arch, at the same time, this effect is affected by the height of the head, the higher the head height, the more obvious effect. According to the numerical results, the spatial location of the cavern has less effect on the lining water pressure under the conventional drainage system, but has a greater effect on the pressure reduction performance of the new three-way drainage system, which is mainly manifested in the right under the> right under the 45°>right>right upper 45°>top, when the cave is located in the lower 45° right and lower, the water pressure curve shows a “peak shape”, and with the density of the reverse drainage pipe increases, the more obvious the effect of pressure reduction, the more significant the water pressure curve “peak shape”. The water pressure curve “peak shape” is more significant. In order to remove the effect of high water pressure in the elevated arch, the diameter of the reverse drain pipe was increased at the elevated arch location in the middle of the tunnel, which was found to be effective in reducing the peak effect of high water pressure and ensuring that the tunnel structure is locally protected from the threat of high water pressure.