A process for preparing a supported metallocene catalyst for olefin polymerization, which comprises adding a cocatalyst compound to at least one transition metal compound; or adding a cocatalyst compound to a carrier; supporting the transition metal compound obtained in step on a carrier, or supporting a transition metal compound to the carrier obtained in step; and primarily treating the supported catalyst with a solution or suspension of an antistatic agent; and then washing the supported catalyst with a solvent and drying it; and secondarily treating the supported catalyst with dry powder of an antistatic agent, wherein the transition metal compound is represented by Formula 1: in Formula 1, M is a transition metal of Group 4 of the Periodic Table of the Elements; Q is any one of carbon, silicon, germanium, and tin, X is each independently a halogen atom, an alkyl group having 1-10 carbon atoms, or an alkenyl group having 2-10 carbon atoms, R 1 to R 12 may each independently be one of a hydrogen atom, an alkyl group having 1-20 carbon atoms, a cycloalkyl group having 3-6 carbon atoms, and an aryl group having 6-14 carbon atoms, or when two adjacent R n and R n+1 (where n is 1 to 11) among R 1 to R 12 form a mono- or multi-cyclic compound having 1-15 carbon atoms unsubstituted or substituted with an alkyl group having 1-4 carbon atoms, other Rs than R n and R n+1 may each independently be one of hydrogen, an alkyl group having 1-20 carbon atoms, a cycloalkyl group having 3-6 carbon atoms, and an aryl group having 6-14 carbon atoms, and R 13 and R 14 are each independently an alkyl group having 1-10 carbon atoms or an aryl group having 6-14 carbon atoms, wherein the antistatic agent used in step and the antistatic agent used in step comprises at least one selected from the group consisting of aluminum stearate, sodium stearate, calcium stearate, zinc stearate, aluminum tristearate, aluminum acetate, and zinc acetate, wherein the amount of the antistatic agent used in step is 0.01 to 5.0% by weight based on the total weight of the supported catalyst, and the amount of the antistatic agent used in step is 0.1 to 3.5% by weight based on the total weight of the supported catalyst, and wherein the amount of the transition metal compound supported on the carrier is 0.5 to 3.0% by weight based on the total weight of the supported catalyst, and the amount of the cocatalyst compound supported on the carrier is 20 to 30% by weight based on the total weight of the supported catalyst. in Formula 1, M is a transition metal of Group 4 of the Periodic Table of the Elements; Q is any one of carbon, silicon, germanium, and tin, X is each independently a halogen atom, an alkyl group having 1-10 carbon atoms, or an alkenyl group having 2-10 carbon atoms, R 1 to R 12 may each independently be one of a hydrogen atom, an alkyl group having 1-20 carbon atoms, a cycloalkyl group having 3-6 carbon atoms, and an aryl group having 6-14 carbon atoms, or when two adjacent R n and R n+1 (where n is 1 to 11) among R 1 to R 12 form a mono- or multi-cyclic compound having 1-15 carbon atoms unsubstituted or substituted with an alkyl group having 1-4 carbon atoms, other Rs than R n and R n+1 may each independently be one of hydrogen, an alkyl group having 1-20 carbon atoms, a cycloalkyl group having 3-6 carbon atoms, and an aryl group having 6-14 carbon atoms, and R 13 and R 14 are each independently an alkyl group having 1-10 carbon atoms or an aryl group having 6-14 carbon atoms, wherein the antistatic agent used in step and the antistatic agent used in step comprises at least one selected from the group consisting of aluminum stearate, sodium stearate, calcium stearate, zinc stearate, aluminum tristearate, aluminum acetate, and zinc acetate, wherein the amount of the antistatic agent used in step is 0.01 to 5.0% by weight based on the total weight of the supported catalyst, and the amount of the antistatic agent used in step is 0.1 to 3.5% by weight based on the total weight of the supported catalyst, and wherein the amount of the transition metal compound supported on the carrier is 0.5 to 3.0% by weight based on the total weight of the supported catalyst, and the amount of the cocatalyst compound supported on the carrier is 20 to 30% by weight based on the total weight of the supported catalyst.