Fracture　structures　commonly　have　negative　impacts　on　the　strength　and　safety　of　rock　mass,　and　various　combinations　of　2D　and　3D　flaws　make　the　destruction　procedure　becomes　more　complicated.　Therefore,　laboratory　tests　based　on　three　types　of　flawed　rocks　(symmetric　twin　flaws　with　different　2D-3D　occurrences)　are　finished　to　detect　the　mechanical,　optical　and　acoustic　characteristics　of　fractured　rocks　during　the　uniaxial　compression　test;　PFC3D　simulations　are　conducted　for　analyzing　the　deformation　features,　principal　stress　distributions,　and　detailed　failure　mechanism　of　the　fractured　rocks.　The　main　results　are　as　follows:　1)　Different　combinations　of　2D　&　3D　preset　flaws　directly　influence　the　results　of　deformation,　stress　distribution,　and　failure　developments.　2)　Rotation　of　the　intermediate　stress　axes　only　appear　near　the　flaw　inclination　boundary　(when　the　monitoring　position　moves　outwards),　while　the　directions　of　intermediate　principal　stress　axes　remain　stable　near　the　flaw　strike　boundary.　3)　Separating　cracks　by　various　occurrences　helps　to　construct　local　failures　along　different　directions,　and　make　some　local　failures　visible　and　clear;　the　traditional　cracks　(short　line　or　thin　oval　shape)　are　induced　by　the　uneven　deformation　in　x-o-z　planes,　and　the　separated　cracks　(wide　oval　or　standard　disc　shape)　result　from　the　uneven　deformation　in　y-o-z　planes.　4)　Surrounding　rocks　at　different　positions　suffer　various　modes　of　failures,　the　non-ignorable　thickness　of　preset　flaw　leads　to　simultaneous　Mode　I　and　Mode　II　failure　at　the　flaw　tip,　and　the　mixed　Mode　II&III　failure　only　occurs　in　the　rocks　adjacent　to　the　flaw　strike　boundary.