Mountain　tunnels　often　pass　through　active　fault　zones　due　to　the　restriction　of　route　planning.　The　activities　of　fault　zones　affect　the　safety　of　the　tunnel　structure　that　intersects　them.　Therefore,　post-earthquake　reconnaissance　was　conducted　to　investigate　the　damage　characteristics　of　tunnels　crossing　strike-slip　faults.　Based　on　Xianglu　Mountain　tunnel　of　water　diversion　project　in　central　Yunnan　province,　a　three-dimensional　finite　element　analysis　model　of　tunnel-fault　system　was　established　to　investigate　the　deformation　characteristics　of　critical　cross　section　of　tunnel　under　strike-slip　faulting.　Based　on　the　established　finite　element　model,　parametric　analysis　was　performed　to　investigate　the　effects　of　the　fault　displacement,　fault　width　and　the　intersection　angle　using　the　relative　displacement　method.　The　results　show　that　the　deformation　mode　of　cross　section　is　horizontal　ellipse　for　the　intersection　angle　of　45.　For　the　intersection　angle　of　135,　the　deformation　mode　of　cross　section　is　upright　ellipse.　The　deformation　of　tunnel　cross　section　located　in　the　center　of　the　fault　fracture　zone　is　reduced　with　the　increase　of　the　fault　width.　The　areas　with　the　most　severe　deformation　in　the　cross　section　of　tunnel　appear　in　the　vault　and　the　bottom　of　the　tunnel　lining　under　strike-slip　faulting,　which　needs　to　be　concerned　in　the　design　of　mountain　tunnels.　©　2020,　Editorial　Office　of　Journal　of　Building　Structures.　All　right　reserved.