In　this　study,　a　group　of　experiments　using　true　triaxial　stress　conditions　with　free　face　loading　are　performed　on　granite　specimens　with　non-penetrating　double　flaws.　The　crack　development　and　failure　characteristics　of　these　specimens　are　explored　by　integrating　video　of　the　free　face　and　acoustic　emission　technology,　with　the　combination　of　the　four　different　intermediate　principal　stresses　and　three　different　grain　sizes　of　the　granite　chosen　as　variables.　First,　surface　flaws　with　a　depth　of　50　mm　are　found　to　have　limited　influence　on　the　specimen＇s　failure　mode.　The　intermediate　principal　stress　has　a　greater　effect　as　it　inhibits　the　development　of　surface　cracks;　however,　surface　cracks　develop　much　more　readily　in　coarse-grained　specimens　than　in　other　specimens.　Second,　when　the　intermediate　principal　stress　exceeds　10　MPa,　the　rock　burst　failure　phenomenon　occurs　in　the　specimen.　Third,　irrespective　of　changes　in　the　intermediate　principal　stress　and　granite　specimen　grain　size,　the　specimens　primarily　fail　by　tensile-shear　failure　and　shear　failure.　Extending　inward　from　the　free　face　in　the　sigma　3　direction,　according　to　the　failure　types,　the　failure　types　can　be　classified　into　tensile　failure,　shear　failure,　and　tensile-shear　failure.　Finally,　using　the　stress　state　synthesis　method,　the　specimen＇s　stress　state　and　crack　distribution　mechanism　on　the　sigma　2　loading　plane　are　analyzed.