Cubic　Sillenite　Bi25FeO40　(BFO)　could　become　a　new　magneto-optical　material　due　to　its　high　concentration　of　Bi3+　and　no　birefringence.　But　its　weak　magnetism　causes　the　magneto-optical　properties　to　be　far　from　the　requirements　of　practical　applications.　Doping　magnetic　Fe3+　and　Ni2+　ions　to　improve　the　magnetism　and　magneto-optical　properties　of　BFO　(Bi19Ni2.8Fe4.2O40)　film　on　fluorine-doped　tin　oxide　(BNFO/FTO)　is　discussed　in　this　paper.　Another　focus　of　this　paper　is　to　discuss　the　magneto-optical　properties　modulated　by　the　electric　field.　The　cubic　BNFO　film　has　weak　piezoelectric　effects,　which　makes　it　difficult　to　modulate　its　magnetooptical　effect　by　electric　field.　A　polarity　symmetry　induced　by　the　Schottky　junction　between　Au　metal　layer　and　BNFO　semiconductor　layer　(Au/BNFO)　compensates　for　cubic　symmetry,　and　the　piezoelectric　effect　can　be　improved.　By　applying　an　electric　field,　its　magnetic　circular　dichroism　(MCD)　ellipticity　|Psi　F|　gradually　decreases　as　a　direct　current　voltage　from　0　V　to　10　V　in　a　magnetic　field　of　2500　Oe,　demonstrating　the　feasibility　of　this　strategy.　These　results　indicate　a　new　way　for　highly　symmetric　magneto-optical　materials　to　modulate　magneto-optical　effects　in　electric　fields.