Summary: The effect of the Coriolis and buoyancy forces on the turbulent heat transfer disturbed by rib turbulators was numerically investigated by using the large eddy simulation (LES). The computational condition was as follows: the turbulent Reynolds number of 350, the rotation number of 1.0, the rib angles of \(90^{\circ}\) and \(60^{\circ}\), and the Rayleigh number from \(-5\times 10^4\) to \(+5\times 10^4\). The heat transfer was enhanced and suppressed by the buoyancy-induced aiding and opposing flows, respectively. The friction factor was dominated by the form drag, and the results of \(90^{\circ}\) and \(60^{\circ}\) rib showed different behavior for the Rayleigh number change.