Research　purposes:　Taking　the　Wukeng　Tunnel　of　the　Longyan-Xiamen　Railway　as　an　example,　basing　on　the　analysis　of　the　engineering　properties　of　the　diabase　and　the　on-site　monitored　data,　this　paper　studies　the　pressure　of　the　surrounding　rock　in　the　section　of　the　diabase　dikes,　the　deformation　characteristics　of　the　tunnel　and　the　formation　mechanism　that　causes　the　large　tunnel　deformation　to　provide　the　guidance　for　the　design　and　construction　of　the　similar　tunnels.　Research　conclusions:　(1)　The　diabase　is　rich　in　kaolinite,　with　the　engineering　properties　of　low　strength,　easy　disintegration　and　weak　expansion,　but　it　is　dilatable　along　the　unloading　direction　under　the　unloaded　stress　path.　(2)　The　distribution　of　the　diabase　dikes　has　the　significant　effect　on　the　magnitude　and　distribution　of　the　rock　pressure.　The　pressure　of　the　surrounding　rock　with　exposing　more　diabase　section　is　bigger　than　that　with　exposing　less　diabase　section,　and　the　pressure　of　the　exposing　part　is　bigger　than　that　of　the　adjacent　parts　without　exposure.　(3)　The　distribution　of　diabase　dikes　also　affect　the　tunnel　deformation　significantly.　The　settlement　of　the　vault　with　exposing　the　section　is　larger.　In　the　section　of　exposing　the　diabase　on　the　dome,　the　convergence　deformation　of　the　sidewall　is　larger.　In　the　section　of　exposing　the　diabase　on　the　sidewall　and　arch,　the　tunnel　deformation　lasts　longer.　(4)　In　the　section　of　exposing　more　diabase,　the　large　tunnel　deformation　contains　the　swelling　deformation　and　compressional　deformation.　(5)　This　research　result　can　be　available　for　the　design　and　construction　of　tunnel　in　diabase　zone.