The eigenmodes of bent rib and bent strip waveguides are calculated by accurate and rigorous full vectorial mode matching method. Mode index and bending loss are presented as functions of bending radius. The computation result shows an excellent agreement with that obtained by finite difference method. Comparison of the strip waveguides with radius of 12 and 50 μm indicates that the phenomena of TE-TM coupling occurring on the side wall will become very strong when the bending radius is decreased, and this is the reason why the modes in the bend waveguide with small radius are hybrid mode instead of TE mode or TM mode in the traditional sense. The difference between transverse components of hybrid mode will be abated if the bending loss decreased, and when the two components are comparable, the polarization dependence of bent waveguide will decrease greatly.