Objeclive To understand the effects of the arterial size on the hemodynamics of S-shaped arteries. Method Numerical simulation method was applied to analyze the temporal and spatial distributions of hemodynamic variables in bothlarge and small S-shaped arterial models with different arterial diameters under identical boundary conditions, respectively. Result The secondary flow in the large S-shaped artery is more complex than that in the small one; stronger eddy flow occurred in the inner bends of curved arteries; pressure and wall shear stresses changed violently in the curved arteries, especially in the larger model. Conclusion The hemodynamics of S-shaped arteries may affect the function of arterial endothelium, and result in the thickening of the intima. It may be favorable to avoid using the S-shaped artery in operations to correct or bypass arterial stenosis when utilizing prosthetic or autologous vessels.