Reliable measurement of CO2 diffusion coefficient in consolidated oil-saturated porous media is critical for design, performance of carbon capture and storage (CCS) and CO2 enhanced oil recovery (EOR) project. In this study, a thorough experimental investigation on supercritical CO2 diffusion in n-decane saturated Berea core (50 and 100 mD) was conducted at elevated pressure (10 to 25 MPa) and temperature (333.15 to 373.15 K), which simulated the real reservoir condition. Supercritical CO2 diffusion coefficients in Berea core were calculated by a model appropriate for diffusion in porous media based on Fick’s law. The results show that with an increase in pressure, temperature and permeability, the supercritical CO2 diffusion coefficient increases correspondingly. The supercritical CO2 diffusion coefficient first increases slowly at 10 MPa and then grow significantly with the increase of pressure. The effect of temperature becomes weaker at elevated pressure condition. And the effect of permeability keeps steady despite of temperature change in experiments. The effect of gas state and porous media on supercritical CO2 diffusion coefficient is further discussed by comparing the results in this study with previous research. Based on the experimental results, an empirical correlation for supercritical CO2 diffusion coefficient in n-decane saturated porous media is developed. The experimental results contribute to the study of supercritical CO2 diffusion in compact porous media.