Due　to　the　small　work　function　and　large　resistance　of　intrinsic　graphene,　graphene-silicon　Schottky　junction　solar　cells　have　low　VOC　and　JSC.　For　those　problems,　AFORS-HET　is　used　to　simulate　the　graphene-silicon　Schottky　junction　solar　cells.　The　simulation　results　show　that　the　VOC　can　be　improved　with　the　increase　of　the　band　gap,　acceptor　concentration　and　work　function　of　graphene.　With　the　increase　of　the　donor　concentration　of　crystal　silicon,　the　VOC　is　reduced　from　494.1　mV　to　386.6　mV.　Finally,　optimum　efficiency　of　11.92%　has　been　achieved　after　simulating　the　thickness　of　crystal　silicon　and　graphene　layer,　which　is　the　maximum　value　of　this　kind　of　structure　reported　at　present.　©　2020,　Solar　Energy　Periodical　Office　Co.,　Ltd.　All　right　reserved.