In　this　study,　the　high-quality　cubic-shaped　single-crystalline　Na0.5Bi0.5TiO3　(NBT)　has　been　successfully　synthesized　by　a　hydrothermal　method,　in　which　their　grain　size　can　be　modulated　effectively　by　both　mineralizer　concentration　and　reactant　concentration.　Our　result　shows　that　the　formation　of　fine　cubic-shaped　NBT　can　be　promoted　by　increasing　the　mineralizer　concentration,　while　be　inhibited　by　increasing　the　reactant　concentration　as　a　whole.　However,　further　higher　mineralizer　concentration　or　lower　reactant　concentration　may　lead　to　a　smaller　grain　size　in　NBT.　From　our　results,　it　is　suggested　that,　to　synthesize　a　big　single　crystalline　of　NBT,　a　suitable　mineralizer　and　reactant　concentration　should　be　carefully　considered.　Interestingly,　it　is　also　found　that　the　one-dimensional　nanostructure　may　be　more　inclined　to　form　Na-Ti-O　(NT)　compounds　rather　than　NBT　phase.　And　the　growth　mechanism　and　a　possible　growth　model　have　been　presented.　Our　result　presents　a　simple　and　green　technical　preparation　route　for　the　low-cost　and　high-quality　NBT　single　crystalline　with　self-designed　shape　and　size.