The　seismic　damage　of　mountain　tunnels　is　closely　associated　with　the　movement　of　active　faults.　Seismic　design　of　tunnels　crossing　active　faults　is　one　of　the　great　challenges　nowadays.　Based　on　the　engineering　prototype　of　the　Xianglu　mountain　tunnel,　the　water　diversion　project　in　central　Yunnan　Province,　a　numerical　method　to　simulate　the　propagation　of　normal　fault　rupture　is　proposed　using　the　finite　element　method　incorporated　with　the　cohesive　interface　model　in　fracture　mechanics.　The　proposed　method　is　verified　against　the　post-earthquake　reconnaissance　and　experimental　results　using　the　three-dimensional　free-field　model.　It　is　used　to　simulate　a　tunnel　crossing　a　normal　fault,　and　the　effects　of　fault　displacement　and　dip　angle　on　the　response　of　the　tunnel　linings　are　discussed.　Besides,　the　damage　indices　and　safety　assessment　criteria　are　introduced　to　preliminarily　evaluate　the　damage　of　the　tunnel　linings　subjected　to　fault　movement.　The　results　show　that　the　mechanisms　of　surface　rupture　exhibit　the　forms　of　folding　or　fault　scarps　under　normal　faulting.　The　axial　tensile　strain　and　hoop　shear　strain　of　the　tunnel　linings　reach　the　maximum　at　the　position　where　they　intersect　the　fault　slip　surface.　The　seismic　damage　state　of　tunnel　along　the　longitudinal　direction　is　significantly　affected　by　the　fault　displacement　and　dip　angle.　The　length　of　the　tunnel　linings　in　a　severely　damaged　and　completely　damaged　state　is　significantly　reduced　with　the　increase　of　the　dip　angle.　Dip　angles　of　50°　to　70°　are　more　detrimental　to　structural　safety.　©　2020,　Editorial　Office　of　Chinese　Journal　of　Geotechnical　Engineering.　All　right　reserved.