Shape-inducedphasetransitionofvortexdomainstructures(VDSs)inBaTiO_3(BT)nanodotsunderopencircuitboundaryconditionhavebeeninvestigatedusinganeffectiveHamiltonianmethod.OurcalculationindicatesthetetragonalVDSmissingincubicBTnanodotscanbeinducedbyvaryingtheshapeofananodotfromcubetoplatelet.Interestingly,anovelVDSisfoundinBTnanoplateletsinoursimulations.Furtherinvestigationshowsthatitisaresultofcompromisebetweenthegroundstateandthesymmetryoftheshapeofthenanodot.Furthermore,basedonthenovelVDS,routesofcontrollingVDSsgovernedbyhomogeneouselectricfieldanduniformstressarediscussed.Inparticular,ourresultsshowthepossibilityofdesigningmulti-statesdevicesbasedonasingleVDS.