In　this　paper,　generation　of　twist　grain　boundaries　(TGBs)　and　their　effects　on　the　mechanical　behaviors　of　graphene/aluminum　(Gr/Al)　nanolaminated　composites　were　studied　via　molecular　dynamics　(MD)　method.　Crystallization　of　the　Gr/Al　composite　was　conducted　to　observe　the　microstructural　evolution.　The　whole　evolution　process　including　nucleation　and　growth　of　crystals　was　presented.　TGBs　were　formed　between　the　adjacent　crystals　after　crystallization.　The　fcc　(1　1　1)　plane　of　the　Al　matrix　has　three-fold　symmetry,　so　that　the　TGB　angles　can　range　from　0　degrees　to　60　degrees.　Tensile　tests　on　the　Gr/Al　composites　with　TGBs　were　carried　out　to　study　their　deformation　behavior.　The　results　showed　that　the　graphene-nanoplate　(GNP)　and　TGBs　greatly　impact　on　the　dislocation　behavior　of　the　Al　matrix.　The　dependences　of　dislocation　nucleation　and　evolution　on　the　TGB　angle　were　uncovered.　The　TGB　also　plays　a　significant　role　in　blocking　dislocation　motion,　and　the　effectiveness　mainly　depends　on　its　strength.　The　variations　of　yield　stress　and　strain　of　the　Gr/Al　composites　with　different　TGB　angles　were　also　predicted.　It　was　revealed　that　failure　of　the　composite　is　caused　by　combined　action　of　tensile　deformation　and　shear　deformation　induced　by　defects　at　the　GNP　edge.