True　triaxial　experiment　with　a　synchronous　acoustic　emission　(AE)　monitoring　system　is　a　popular　measure　for　the　assessment　of　strength　and　cracking　behaviors　of　brittle　flawed　rocks　under　anisotropic　stress　circumstances.　This　measure　was　employed　to　investigate　the　laboratory-scale　brittle　failure　of　flawed　sandstone　containing　two　different　en　echelon　flaw　configurations.　Quantitative　interpretations　and　comparisons　of　acousto-mechanical　properties　and　cracking　behaviors　in　intact　and　flawed　sandstone　have　become　available.　Observations　first　revealed　that　en　echelon　flaws　considerably　weakened　rock　strength　and　deformability,　and　strongly　affected　the　damage　and　failure　processes.　Second,　intact　specimen　showed　a　quasi-2D　spallation　failure,　while　the　failure　of　flawed　specimens　was　dominated　by　the　induced　cracks　initiated　from　en　echelon　flaws.　Third,　the　two　fundamental　failure　types　of　rock　bridge　including　tensile-dominated　failure　and　shear-dominated　failure　were　registered.　Whatever　the　failure　type,　micro-shear　failure　mechanism　co-existed　with　micro-tensile　failure　mechanism.　Moreover,　AE　amplitude　distributions　at　the　stable　and　unstable　cracking　phases　follow　a　power　law.　The　current　findings　provide　insights　into　the　brittle　failure　mechanisms　of　flawed　rocks　and　have　significant　implications　at　scales　relevant　to　seismicity　and　engineering　applications.