In order to investigate the effects of the Coriolis force and the duct cross-sectional aspect ratio on turbulent heat transfer, the large eddy simulation was performed changing the aspect ratio and the rotation number in the range, 0.25-4.0 and 0-5.0, respectively, while the turbulent Reynolds number was 350. In the results, both direct and indirect influences of the Coriolis force on the turbulence were seen, The relative intensity of these influences depended on the aspect ratio. The Colburn＇s j factor showed a higher value for a larger aspect ratio because of larger heal transfer enhancement on the pressure and side surfaces.