This　paper　presents　a　method　of　determining　reasonable　anti-fault　fortification　length　and　studies　the　effect　of　different　deformation　joint　spacing　for　tunnels　within　the　active　faults　region.　The　length　determination　criterion　is　based　on　the　law　that　the　internal　force　and　stress　of　lining　gradually　decrease　and　then　remain　stable　along　the　fault　fracture　plane.　Besides　the　determination　of　fortification　length,　the　deformation　joint　spacing　is　set　to　6m,　9m　and　12m　respectively　within　the　fortification　length　to　study　and　compare　their　effect　on　the　internal　force　and　stress　of　lining.　These　analyses　indicate　that　the　anti-fracture　fortification　length　is　determined　to　be　90m,　setting　the　deformation　seam　can　significantly　reduce　the　internal　force　and　stress　of　lining　and　with　the　decrease　of　deformation　joint　spacing,　the　anti-fault　effect　is　better.　©　2019　Associazione　Geotecnica　Italiana,　Rome,　Italy.