To study the flow characteristics of water and oil in a free surface vortex with an oil slick on the water surface, the flow phenomenon was simulated using FLUENT software and compared with the experimental phenomenon. The volume of the fluid model was used to obtain the oil−gas−water threephase eddy current field, yielding the flow structure and evolution process of the free surface vortex. The results reveal that the oil and water distribution follows a specific rule, from the beginning of the vortex at the free surface, through continuous downward extension and finally reaching stability. A few other parameters were also calculated, including the vertical distribution of the vortex core radius, the maximum tangential velocity and the radial velocity at the vortex core radius, and the variation of the velocity components of each phase in the flow field with position and time. The research reveals the oil transportation characteristics of free surface vortices and provides a method for recovering an oil slick using its surface vortex characteristics