Provided are a plasticizer composition, a resin composition and a method of preparing the same. Particularly, a plasticizer comprising a cyclohexane 1,4-diester based material and a citrate-based material. The plasticizer is capable of improving physical properties such as plasticization efficiency, migration, tensile strength, elongation rate, stress migration and light fastness, which are required for sheet formulations, when used as a plasticizer for the resin composition by improving poor physical properties generated due to a structural limitation thereof, and a resin composition including the same are provided.