Provided is a method of preparing a rubber composition, which includes (a) reacting a conjugated diene-based monomer with one or more of compounds in the presence of a first catalyst; (b) adding a conjugated diene-based monomer to a product of the step (a) and inducing a reaction; and (c) adding a second catalyst and a conjugated diene-based monomer to a product of the step (b) and inducing a reaction.