Abstract: In order to understand the influence of earth-rock interface height of the shallow-buried loess tunnel on safety of primary support structure, the effect of earth-rock interface height and position on safety of primary support is studied by numerical simulation based on the Linxian tunnel. The results show that: the earth-rock interface results in sudden change of safety factor of the primary support structure and the distribution of safety factor is asymmetric when the interface is inclined. Under the same buried depth, the asymmetric pressure above the earth-rock interface decreases while the asymmetric pressure below the earth-rock interface increases with downward movement of the earth-rock interface. Under the same interface depth, the asymmetric pressures of the left and right sections of the primary support increase with the increase of the buried depth. When the earth-rock interface is located in upper heading,middle heading and lower heading, and the interface inclination is 10°, the load can be calculated by increasing the load by 20% on the left side of tunnel or reducing resistance coefficient by 20% on the right side of tunnel.