A method of preparing an anode slurry for a secondary battery, the method comprising: preparing a composite by dispersing a conductive material in an aqueous binder and then mixing with a semi metal oxide or metal oxide, wherein the preparing of the composite is performed by a spray drying method; and mixing the composite with a carbon material and a non-aqueous binder, wherein the carbon material is included in an amount ranging from 20 parts by weight to 80 parts by weight based on a total weight of the composite, wherein the composite comprises: a semi metal oxide or metal oxide; a conductive material on a surface of the semi metal oxide or metal oxide; and the aqueous binder, wherein the conductive material is selected from the group consisting of carbon black selected from the group consisting of acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers selected from the group consisting of carbon fibers and metal fibers; powder selected from the group consisting of fluorocarbon powder, aluminum powder, and nickel powder; conductive whiskers selected from the group consisting of zinc oxide and potassium titanate; conductive metal oxide including titanium oxide; and a polyphenylene derivative, wherein the carbon material comprises one or more selected from the group consisting of soft carbon, hard carbon, natural graphite, artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fibers, mesocarbon microbeads, mesophase pitch, petroleum-derived cokes, and coal-derived cokes, wherein the non-aqueous binder comprises one or more selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, and polypropylene, and wherein the aqueous binder comprises one or more selected from the group consisting of a styrene-butadiene rubber, an acrylonitrile-butadiene rubber, an acrylonitrile-butadiene-styrene rubber, carboxymethyl cellulose, and hydroxypropyl methylcellulose. preparing a composite by dispersing a conductive material in an aqueous binder and then mixing with a semi metal oxide or metal oxide, wherein the preparing of the composite is performed by a spray drying method; and mixing the composite with a carbon material and a non-aqueous binder, wherein the carbon material is included in an amount ranging from 20 parts by weight to 80 parts by weight based on a total weight of the composite, wherein the composite comprises: a semi metal oxide or metal oxide; a conductive material on a surface of the semi metal oxide or metal oxide; and the aqueous binder, wherein the conductive material is selected from the group consisting of carbon black selected from the group consisting of acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers selected from the group consisting of carbon fibers and metal fibers; powder selected from the group consisting of fluorocarbon powder, aluminum powder, and nickel powder; conductive whiskers selected from the group consisting of zinc oxide and potassium titanate; conductive metal oxide including titanium oxide; and a polyphenylene derivative, wherein the carbon material comprises one or more selected from the group consisting of soft carbon, hard carbon, natural graphite, artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fibers, mesocarbon microbeads, mesophase pitch, petroleum-derived cokes, and coal-derived cokes, wherein the non-aqueous binder comprises one or more selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, and polypropylene, and wherein the aqueous binder comprises one or more selected from the group consisting of a styrene-butadiene rubber, an acrylonitrile-butadiene rubber, an acrylonitrile-butadiene-styrene rubber, carboxymethyl cellulose, and hydroxypropyl methylcellulose. a semi metal oxide or metal oxide; a conductive material on a surface of the semi metal oxide or metal oxide; and the aqueous binder, wherein the conductive material is selected from the group consisting of carbon black selected from the group consisting of acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers selected from the group consisting of carbon fibers and metal fibers; powder selected from the group consisting of fluorocarbon powder, aluminum powder, and nickel powder; conductive whiskers selected from the group consisting of zinc oxide and potassium titanate; conductive metal oxide including titanium oxide; and a polyphenylene derivative, wherein the carbon material comprises one or more selected from the group consisting of soft carbon, hard carbon, natural graphite, artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fibers, mesocarbon microbeads, mesophase pitch, petroleum-derived cokes, and coal-derived cokes, wherein the non-aqueous binder comprises one or more selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, and polypropylene, and wherein the aqueous binder comprises one or more selected from the group consisting of a styrene-butadiene rubber, an acrylonitrile-butadiene rubber, an acrylonitrile-butadiene-styrene rubber, carboxymethyl cellulose, and hydroxypropyl methylcellulose.