Vertically　oriented　graphene　(VG)　has　attracted　attention　for　years,　but　the　growth　mechanism　is　still　not　fully　revealed.　The　electric　field　may　play　a　role,　but　the　direct　evidence　and　exactly　what　role　it　plays　remains　unclear.　Here,　we　conduct　a　systematic　study　and　find　that　in　plasma-enhanced　chemical　vapor　deposition,　the　VG　growth　preferably　occurs　at　spots　where　the　local　field　is　stronger,　for　example,　at　GaN　nanowire　tips.　On　almost　round-shaped　nanoparticles,　instead　of　being　perpendicular　to　the　substrate,　the　VG　grows　along　the　field　direction,　that　is,　perpendicular　to　the　particles＇　local　surfaces.　Even　more　convincingly,　the　sheath　field　is　screened　to　different　degrees,　and　a　direct　correlation　between　the　field　strength　and　the　VG　growth　is　observed.　Numerical　calculation　suggests　that　during　the　growth,　the　field　helps　accumulate　charges　on　graphene,　which　eventually　changes　the　cohesive　graphene　layers　into　separate　three-dimensional　VG　flakes.　Furthermore,　the　field　helps　attract　charged　precursors　to　places　sticking　out　from　the　substrate　and　makes　them　even　sharper　and　turn　into　VG.　Finally,　we　demonstrate　that　the　VG-covered　nanoparticles　are　benign　to　human　blood　leukocytes　and　could　be　considered　for　drug　delivery.　Our　research　may　serve　as　a　starting　point　for　further　vertical　two-dimensional　material　growth　mechanism　studies.