Objective To explore the feasibility of polyethylene glycol-coated gold-nanoparticles (PEGlatedAuNPs) as a new CT contrast agent. Methods In vitro CT scanning was performed on seven different concentrations of PEGelatedAuNPs and non-ionic iodine contrast agent iopromide, and the attenuation coefficient and imaging ability were compared. In vivo CT scanning was also performed after the animals were subcutaneously injected and intravenous injected with PEGelatedAuNPs and non-ionic iodine contrast agent iopromide to evaluate the enhancement characteristics of various organs in vivo. Results The attenuation coefficient of PEGelatedAuNPs was higher than that of iopromide when the agents were at the same concentration. In addition, the difference of CT values between PEGelatedAuNPs and iopromide increased with the increase of the agent concentration. The PEGelatedAuNPs is stable under the skin and can stay for a long time without being easily absorbed. The PEGelatedAuNPs has good biocompatibility in SD rats, possesses a long circulation time in the body and is mainly metabolized by the liver. Conclusion PEGlatedAuNPs is an ideal CT molecular imaging contrast agent.