A method for preparing an emulsion composition containing an organopolysiloxane that is capped with a trialkylsilyl group and has a viscosity at 25°C of at least 50,000 mm 2 /s, the method comprising the steps of, in order: (i) preparing an emulsion composition by emulsifying a mixture containing: 100 parts by weight of an organopolysiloxane of general formula below, having an octamethylcyclotetrasiloxane content not more than 1,000 ppm HO(R 1 2 SiO) n H wherein each R 1 independently is a hydrogen atom or a substituted or unsubstituted hydrocarbon group of 1 to 20 carbon atoms, and n is a number such that the organopolysiloxane has a viscosity at 25°C of from 25 to 20,000 mm 2 /s, 0 to 100 parts by weight of nonionic surfactant, 0 to 100 parts by weight of anionic surfactant, (D-1) 0 to 100 parts by weight of acidic compound; provided that the combined amount of, and (D-1) is at least 0.1 part by weight, and (E-1) 1 to 10,000 parts by weight of water; (ii) adding to the resulting emulsion composition: (D-2) 0 to 25 parts by weight of acidic compound, provided that the combined amount of (D-1) and (D-2) is at least 0.1 part by weight, and (E-2) 0 to 10,000 parts by weight of water, and subsequently carrying out emulsion polymerization at a temperature below 40°C until the viscosity at 25°C of the organopolysiloxane becomes at least 50,000 mm 2 /s; and (iii) adding at least 0.001 part by weight of: organosilicon compound of general formula or below R 2 3 SiOH R 2 3 SiO(R 3 2 SiO) m SiR 2 3 wherein each R 2 independently is an alkyl group of 1 to 18 carbon atoms which may be interrupted by an oxygen atom, each R 3 independently is a hydrogen atom or a substituted or unsubstituted hydrocarbon group of 1 to 20 carbon atoms, and m is a number such that the viscosity at 25°C of the organosiloxane of formula is from 0.65 to 100 mm 2 /s, and carrying out emulsion polymerization again to form the trialkylsilyl-capped organopolysiloxane, wherein the viscosity is measured with a rotational viscometer. (i) preparing an emulsion composition by emulsifying a mixture containing: 100 parts by weight of an organopolysiloxane of general formula below, having an octamethylcyclotetrasiloxane content not more than 1,000 ppm HO(R 1 2 SiO) n H wherein each R 1 independently is a hydrogen atom or a substituted or unsubstituted hydrocarbon group of 1 to 20 carbon atoms, and n is a number such that the organopolysiloxane has a viscosity at 25°C of from 25 to 20,000 mm 2 /s, 0 to 100 parts by weight of nonionic surfactant, 0 to 100 parts by weight of anionic surfactant, (D-1) 0 to 100 parts by weight of acidic compound; provided that the combined amount of, and (D-1) is at least 0.1 part by weight, and (E-1) 1 to 10,000 parts by weight of water; 100 parts by weight of an organopolysiloxane of general formula below, having an octamethylcyclotetrasiloxane content not more than 1,000 ppm HO(R 1 2 SiO) n H wherein each R 1 independently is a hydrogen atom or a substituted or unsubstituted hydrocarbon group of 1 to 20 carbon atoms, and n is a number such that the organopolysiloxane has a viscosity at 25°C of from 25 to 20,000 mm 2 /s, 0 to 100 parts by weight of nonionic surfactant, 0 to 100 parts by weight of anionic surfactant, (D-1) 0 to 100 parts by weight of acidic compound; provided that the combined amount of, and (D-1) is at least 0.1 part by weight, and (E-1) 1 to 10,000 parts by weight of water; (ii) adding to the resulting emulsion composition: (D-2) 0 to 25 parts by weight of acidic compound, provided that the combined amount of (D-1) and (D-2) is at least 0.1 part by weight, and (E-2) 0 to 10,000 parts by weight of water, and subsequently carrying out emulsion polymerization at a temperature below 40°C until the viscosity at 25°C of the organopolysiloxane becomes at least 50,000 mm 2 /s; and (D-2) 0 to 25 parts by weight of acidic compound, provided that the combined amount of (D-1) and (D-2) is at least 0.1 part by weight, and (E-2) 0 to 10,000 parts by weight of water, and subsequently carrying out emulsion polymerization at a temperature below 40°C until the viscosity at 25°C of the organopolysiloxane becomes at least 50,000 mm 2 /s; and (iii) adding at least 0.001 part by weight of: organosilicon compound of general formula or below R 2 3 SiOH R 2 3 SiO(R 3 2 SiO) m SiR 2 3 wherein each R 2 independently is an alkyl group of 1 to 18 carbon atoms which may be interrupted by an oxygen atom, each R 3 independently is a hydrogen atom or a substituted or unsubstituted hydrocarbon group of 1 to 20 carbon atoms, and m is a number such that the viscosity at 25°C of the organosiloxane of formula is from 0.65 to 100 mm 2 /s, and carrying out emulsion polymerization again to form the trialkylsilyl-capped organopolysiloxane, wherein the viscosity is measured with a rotational viscometer. organosilicon compound of general formula or below R 2 3 SiOH R 2 3 SiO(R 3 2 SiO) m SiR 2 3 wherein each R 2 independently is an alkyl group of 1 to 18 carbon atoms which may be interrupted by an oxygen atom, each R 3 independently is a hydrogen atom or a substituted or unsubstituted hydrocarbon group of 1 to 20 carbon atoms, and m is a number such that the viscosity at 25°C of the organosiloxane of formula is from 0.65 to 100 mm 2 /s, and carrying out emulsion polymerization again to form the trialkylsilyl-capped organopolysiloxane, wherein the viscosity is measured with a rotational viscometer.