Disclosed are a thermoplastic polymer combined with a carbon nanomaterial and a method of preparing the same. More particularly, a thermoplastic polymer combined with carbon nanomaterial, comprising 0.1 to 15 wt % of a carbon nanomaterial, 0.025 to 30 wt % of a polycyclic aromatic hydrocarbon derivative, and 55 to 99.875 wt % of a thermoplastic polymer, wherein the carbon nanomaterial and the polycyclic aromatic hydrocarbon derivative combine through π-π interaction, and the polycyclic aromatic hydrocarbon derivative covalently combines with the thermoplastic polymer, is disclosed. The thermoplastic polymer combined with the carbon nanomaterial and the method of preparing the same, according to the present invention, exhibit excellent tensile strength, tensile modulus, electromagnetic shielding effects and anti-static effects, and the like.