Environmental-friendly,　rapid,　and　continuous　preparation　process　of　few-layer　graphene　has　been　developed　by　alternative-current　(AC)　rotating　gliding　arc　plasma,　which　contains　the　characteristics　of　equilibrium　plasma　and　non-equilibrium　plasma.　In　the　process,　methane　was　directly　cracked　in　the　plasma　and　then　graphene　sheets　were　generated.　The　effects　of　hydrogen　and　gas　flow　rate　on　the　yield,　size,　morphology　and　structure　of　graphene　have　been　investigated.　In　addition,　the　formation　mechanism　of　graphene　was　also　revealed　by　using　the　reactive　molecular　dynamic　method.　The　simulation　results　showed　that　the　growth　process　of　graphene　clusters　by　methane　radicals　includes　three　stages:　elongation　of　the　carbon　chains,　cyclization　of　the　carbon　chains,　and　condensation　and　sheeting　of　clusters.　The　carbon　source　concentration　influences　the　graphene　clusters.　Increasing　the　carbon　source　concentration　was　found　to　enlarge　the　size　of　graphene　clusters　but　are　more　prone　to　curling　and　closing.　The　formation　of　C-H　bonds　can　reduce　the　peripheral　dangling　bonds　of　the　clusters,　thereby　delaying　the　closure　of　the　clusters.　It　laid　a　foundation　for　understanding　the　growth　mechanism　of　graphene.