Generally,　cracks　would　lead　in　local　discontinuity　and　sudden　change　in　mode　shape,　and　the　local　entropy　of　beam　mode　will　change　with　the　discontinuity　of　mode　shape.　Based　on　this　property,　cracks　can　be　detected　without　using　a　healthy　mode　shape　serving　as　the　baseline.　This　paper　presents　a　generalised　local　entropy　(GLE)　analysis　method　for　crack　detection　in　beam　structures,　which　is　a　non-baseline　mode　shape-based　damage　detection　algorithm　for　beam-type　structures.　The　fundamental　and　the　second-order　vibration　modes　of　a　cracked　cantilever　beam　are　analysed　with　the　presented　method.　The　proposed　prediction　scheme　is　validated　by　simulations　and　experiments.　Based　on　the　results　obtained　in　this　paper　and　the　qualities　of　simplicity　and　efficiency　of　GLE　method,　a　mode　shape-based　crack　identification　approach　is　developed　as　an　alternative　damage　index　for　structural　health　monitoring　and　non-destructive　testing.