This　paper　describes　a　new　methodology　capable　of　analyzing　coupled　bending　and　torsional　vibrations　in　non-uniform　thin-walled　beams.　The　transfer　matrix　method　(TMM)　and　the　differential　transform　method　(DTM)　are　combined　to　create　the　proposed　transfer　differential　transform　method　(TDTM)　for　solving　equations　coupling　bending　and　torsional　vibrations　in　non-uniform　beams.　Compared　with　the　finite　element　method　(FEM),　the　TDTM　utilizes　a　type　of　changeable　mode　shape　functions　so　that　the　number　of　meshed　elements　can　be　reduced　greatly　when　the　beam＇s　geometric　size　is　uniform.　The　equations　of　motion　of　the　non-uniform　thin-walled　beams　are　established　using　Hamilton＇s　principle.　The　method　considers　both　the　warping　and　rotary　effects　of　the　beam　section.　The　natural　frequencies　and　mode　shapes　of　the　bending　and　torsional　components　are　obtained　using　the　TDTM.　The　accuracy　of　solutions　can　be　controlled　by　the　mesh　density　and　the　series　expansion　order　of　the　mode　shape　whose　ranges　are　also　discussed.　For　illustrative　purposes,　the　natural　frequencies　and　the　frequency　response　curves　of　a　uniform　beam　and　a　non-uniform　beam　are　studied　respectively　and　are　validated　by　experiments.　The　effects　of　warping　and　the　distance　between　the　centroid　of　a　given　section　and　the　corresponding　shear　center　on　the　vibration　properties　of　the　beam　are　also　investigated.