This paper explores the fluid flow and heat transfer behaviors of supercritical carbon dioxide (SCO2) in a tube. The application is utilization of waste heat from a marine gas turbine. The effects of ocean rolling motion on the thermofluid characteristics of SCO2 in a circular tube are numerically investigated based on a verified turbulence model. It is found that the time-averaged heat transfer capacity over a rolling period is improved over static conditions by 7.9%. However, the onset of heat transfer recovery is postponed, and the range of heat transfer deterioration is extended. Under the action of inertial forces due to the rolling motion, heat exchange between cooler/denser and warmer/lighter fluids is enhanced. Secondary circulation is formed when t/tc = 0.325, and the section-averaged heat transfer coefficient is improved by a maximum of 71%. For various periods, a parabolic can be distinctly found in terms of the variation trend of time-averaged heat transfer coefficient, which behaves differently from conventional fluids. Regarding the instantaneous thermal performance, a polarization phenomenon can be observed under severe rolling. With the rise of the layout height, the time-averaged heat transfer performance of the tube increases monotonously, and the maximum increment is 10.64% in studied range.