Considering the characteristics of deep ocean currents, this study numerically investigates the effects of reduced velocity (U*) and rotational speed (α) on the vortex-induced vibration(VIV) response and heat transfer performance of a circular cylinder subjected to oscillatory inflow. The results reveal multiple extrema in the peak amplitude ratios in both the streamwise (A*_peaks，x) and transverse (A*_peaks，y) directions. As α increases, the maximum A*_peaks，x increases, while the corresponding U* decreases. Significant variations are observed in cylinder displacement and lift/drag coefficients with changes in α and U*. The time-averaged displacement in the x-direction increases with U*, whereas the average displacement in the y-direction and the lift coefficient both increase with α. The motion trajectory of the cylinder lacks a distinct pattern within the range of 0≤α≤1.0, but becomes circular at α =1.5. With increasing U*, the average Nusselt number increases, and the distribution of local Nusselt numbers gradually forms a circular pattern. As α increases, the vortex shedding transitions from a 2S pattern to a single-row configuration, with the wake stretching into a U-shaped structure. Temperature field analysis reveals weaker heat exchange at the front stagnation point, while heat transfer and local thermal efficiency at the rear stagnation point are significantly enhanced.