Fault　and　cave　are　two　traditional　fracture　structures　in　the　original　rock　mass.　To　detect　the　specific　failure　characteristic　of　hard　sandstone　containing　fault　and　cave,　two　centrally　symmetrical　sandstone　blocks　are　cemented　together　to　a　cube　combination　specimen;　then　the　true　triaxial　compression　test　is　carried　out,　accompanied　by　acoustic　emission　technology　monitoring　the　development　process　of　micro　fractures.　The　main　results　and　conclusions　are　as　follows:　(1)　The　maximum　horizontal　strain　coincided　with　the　minimum　principal　stress,　and　different　fault　occurrences　affected　the　development　process　of　horizontal　strain.　(2)　Secondary　failure　process　could　be　divided　into　two　stages,　the　first　sudden　stress　drop　phenomenon　accelerated　the　first　round　of　local　failure,　manifested　by　the　relatively　small　axial　strain,　gradually　decreasing　b-values,　higher　AE　(acoustic　emission)　counts,　and　sharp　increase　of　RA　(rising　angle);　the　second　round　of　failure　was　caused　by　the　intrusion　of　the　loading　head,　accompanied　by　the　relatively　large　axial　strain　and　more　complex　failure　modes.　(3)　Different　fault　occurrences　not　only　changed　the　initial　growth　rate　of　lateral　strain　and　final　distance　between　Ε2　and　Ε3,　but　also　impacted　the　occurrence　time　of　maximum　RA　and　the　change　trend　of　AF　(average　frequency).　(4)　The　inclined　fault　and　cement　fill　controlled　the　first　sub-strength　of　composite　rock　specimen,　and　different　cavity　filling　conditions　lead　to　various　failure　modes　during　the　second　round　of　destruction.　The　above　conclusions　can　provide　important　references　for　safety　evaluation　and　smooth　construction　of　engineering　projects　under　similar　condition.　©　The　Author(s),　under　exclusive　licence　to　Springer　Nature　Switzerland　AG　2024.