Amidst　growing　concerns　for　environmental　sustainability　and　green　ecology,　the　utilization　of　Light　Emitting　Diodes　(LEDs)　for　indoor　plant　cultivation　has　emerged　as　an　influential　area　of　research.　Nonetheless,　the　growth　of　indoor　plants　is　often　constrained　by　inadequate　lighting.　Consequently,　designing　novel　LEDs　to　create　an　appropriate　light　environment　has　emerged　as　a　focal　point　in　research.　As　a　new　type　of　photocatalytic　material　with　excellent　optical　properties　and　light　stability,　double　perovskite　has　broad　application　prospects　in　LEDs　manufacturing.　In　this　context,　this　article　aims　to　synthesize　a　new　Ca2Lu(Nb,Mn)O6　double　perovskite　and　study　its　optical　properties　in　LEDs　lighting　for　indoor　plant　growth.　A　new　Ca2Lu(Nb,Mn)O6　double　perovskite　were　synthesized　using　the　traditional　high-temperature　solid-phase　method.　The　crystal　structure　and　luminescence　properties　of　the　double　perovskite　were　characterized　in　detail　using　powder　X-ray　diffraction　(XRD),　Rietveld　refinement,　excitation　and　emission　spectra,　decay　lifetimes,　quantum　efficiency　(QE),　electron　paramagnetic　resonance　(EPR)　spectra,　temperature-dependent　emission　spectra,　and　the　Commission　International　de　l＇Eclairage　(CIE)　color　coordinates.　The　photoelectric　properties　of　Ca2Lu(Nb,Mn)O6　and　Ca2LuNbO6　double　perovskite　have　been　explored　through　first-principles　investigations.　The　absorption　spectra　from　270　to　600　nm　indicates　that　it　can　be　effectively　excited　by　ultraviolet　(UV)　light.　The　emission　spectra　show　a　strong　broad　red　emission　peak　at　684　nm.　The　luminescence　mechanism　has　been　studied　using　the　Tanabe-Sugano　diagram.　In　addition,　the　internal　UV　emission　ratio　beta　1,　crystal　field　strength　Dq,　and　Racah　parameters　B　and　C　were　evaluated.　The　thermal　stability　of　the　sample　was　studied　through　emission　spectra　at　heating　temperatures　from　303　to　573　K.　The　results　indicate　that　Ca2Lu(Nb,Mn)O6　double　perovskite　provides　a　new　solution　for　indoor　plant　growth.