Abstract: The part of Xi'an Metro Line 3 in Xiaozhai which is parallel to ground fissure is taken as the research engineering. The dynamic response of subway tunnels during the coupled load of earthquake and ground fissure sedimentation was studied by the FLAC3D numerical simulation which is based on the finite difference principle. The results show that the peak acceleration of ground reaches maximum near the ground fissure. And the magnification coefficient of PGA gradually decays from the ground fissure to both sides. In ground fissure tunnel horizontal earth pressure increases with PGA.The increase of horizontal earth pressure on the hanging wall is obviously larger than that on the footwall and the curve has a peak at the tunnel. The horizontal earth pressure at the left arch waist is greater than that at the right arch waist and the top in the tunnel. The horizontal earth pressure at the bottom is consistent with that at the left arch waist. It obviously shows that the horizontal earth pressure increases at top. Horizontal earth pressure increases with PGA at the tunnel. The horizontal earth pressure at the left arch waist is greater than that at the right arch waist, but the increase is smaller than that at the right arch waist.