Two-dimensional　(2D)　hexagonal　boron　nitride　(h-BN)　is　considered　as　an　ideal　dielectric　layer　or　substrate　for　other　2D　heterostructure　electronic　devices.　However,　reported　2D　h-BN　films　consist　mostly　of　small　sized　and　randomly　oriented　h-BN　domains,　resulting　in　a　high　density　of　grain　boundaries　during　coalescence.　Here,　we　report　the　growth　of　unidirectionally　aligned　h-BN　domains　in　a　large　area　on　the　Ni(111)　epitaxial　thin　film　on　MgO(111)　substrate　by　ion　beam　sputtering　deposition.　It　is　found　that　the　in-plane　orientation　of　the　underlying　Ni　thin　film,　which　can　be　controlled　by　its　deposition　temperature,　plays　a　key　role　in　the　h-BN　domain　alignment.　Furthermore,　density　functional　theory　calculations　are　performed　to　determine　the　favorable　configuration　of　the　triangular　shaped　h-BN　domains　on　Ni(111).　This　work　provides　a　promising　approach　to　prepare　unidirectionally　aligned　h-BN　domains　in　a　large　area,　and　thus　it　is　possible　to　achieve　wafer-scale　single　crystal　h-BN　by　stitching　these　h-BN　domains.