Motivated　by　the　discovery　of　practical　and　economical　nonlinear　optical　(NLO)　materials　with　strong　second　harmonic　generation　(SHG),　experimental　and　theoretical　researches　have　been　widely　carried　out.　However,　drawbacks　in　one　or　some　respects,　especially　poor　birefringence,　preclude　their　use　for　NLO　applications　in　optoelectronic　technologies.　In　the　present　work,　taking　the　case　of　nonlinear　material　borophosphate　BPO4,　a　systematic　calculation　of　the　structure,　electronic,　linear　and　nonlinear　optical　properties　of　the　BP1-xVxO4　systems　(x　=　0,　0.25,　0.5,　0.75,　and　1)　are　presented　to　tailor　its　small　birefringence　and　assess　their　ultraviolet　NLO　capabilities　based　on　first-principles　calculations.　Particularly,　birefringences　of　the　four　V-containing　compounds　are　significantly　enhanced　to　fulfill　the　phase　matching　conditions　in　the　ultraviolet　region.　Meanwhile,　their　SHG　responses　are　greatly　improved,　especially　for　BP0.5V0.5O4,　with　moderate　optical　anisotropy　of　refraction　(about　0.08　in　transparent　regions)　and　strong　second　harmonic　generation　response　(almost　ten　times　as　compared　with　BPO4).　Besides,　a　detailed　analysis　of　their　electronic　characters,　the　polarizability　anisotropy　and　local　dipole　moments　of　asymmetry　functional　building　[BO4](5-),　[PO4](3-),　and　[VO4](3-)　units　are　elucidated　to　understand　the　high　performance　of　BP1-xVxO4　systems.　These　candidates　would　extend　the　ultraviolet　nonlinear　optical　materials.　Furthermore,　the　strategy　of　introducing　transition　metal　d　orbitals　could　be　a　promising　way　to　tailor　electronic　structures　and　optical　anisotropy　in　other　functional　materials　for　advanced　photonic　devices.