The interfacial tension (IFT) has a significant influence on fluid flow in the supercritical CO2 (scCO(2)) enhanced oil recovery process. However, it is still challenging to demonstrate the effect of scCO(2) on water-oil interface. Therefore, a molecular dynamics simulation is performed to investigate the influence of scCO(2) on the water-decane interface, It is observed that CO2 prefers to accumulate and display surface-active at the water-decane interface. The driving force of CO2 accumulation is the IFT difference between water-decane and water-CO2. The IFT of water-CO2-decane decreases linearly with the increase of CO2. The interactions of water-CO2 and decane-CO2 are strong, and the difference between them is small, providing the mechanism for lowering the IFT of water-decane. The increase in the diffusivity for all fluids toward the interface suggests an increase in the mobility at the water-decane interface due to the addition of CO2, which is in favor of enhancing oil recovery. (C) 2015 Elsevier B.V. All rights reserved.