ZnO　nanoparticles　(ZnO　NPs)　were　obtained　by　a　direct　precipitation　method.　With　the　as.　prepared　ZnO　NPs　as　seeds,　Au/ZnO　heterostructure　was　synthesized　by　seed.　mediated　growth　method　without　any　surfactant,　and　the　diameters　of　ZnO　NPs　and　Au　NPs　were　about　50　nm　and　10　nm,　respectively.　Then　ionic　liquids　(ILs),　trihexyltetradecylphosphonium　bis　(trifluoromethylsulfonyl)　imide　([P(C-6)(3)C-14]　[Tf2N]),　and　functionalized　graphene　(GN)　were　prepared　under　room　temperature.　The　ILs　as　bridges　could　connect　Au/ZnO　heterostructure　to　form　a　new　kind　of　graphene　nanocomposite,　Au/ZnO/GN.　Then　the　penicillinase　and　hematein　were　immobilized　on　Au/ZnO/GN.　And　the　biosensors　based　on　penicillinase.　hematein.　Au/ZnO/GN　(PH-AZG)　were　used　for　detecting　penicillin　G.　In　PBS　buffer　solution　(pH　7.0),　PH-AZG　exhibited　a　detection　range　from　2.5　x　10(-14)　to　3.3　x　10(-6)　mol/L　with　a　detection　limit　of　1.5　x　10(-14)　mol/L　(S/N　＞=　3).　Five　PH-AZG　electrodes　were　prepared　with　the　same　conditions,　and　the　RSDs　for　their　current　response　were　less　than　3.2%.　Furthermore,　the　standard　curves　were　linear　in　the　range　of　5.　10(-14)-5　x　10(-7)　mol/L　for　milk.　The　average　recoveries　were　99.7%　-　101.4%　with　RSDs　of　2.3%　-　3.5%　(n　=　5).　The　method　is　sensitive　and　repeatable,　and　can　be　applied　to　the　field　of　residue　analysis　about　penicillins　G　with　low　concentration　levels.