We analyze and compare the transmission characteristics of the metallic hollow waveguides and dielectric-coated metallic hollow waveguides with different diameters and dielectric layer thicknesses, in terms of attenuation, dispersion, and coupling efficiency. It is shown that a bigger diameter and a thinner dielectric layer can achieve a lower transmission loss. We can coat a dielectric layer to improve the single-mode transmission range and dispersion property. We study the coupling efficiency between a polarized Gaussian beam and the waveguides and find that coupling efficiencies of high-order mode are lower than that of the fundamental mode for a proper optical source. We discuss the influence of the dielectric layer on the coupling efficiency, and also analyze the influence of the dielectric layer on the electric field distribution when the transmission wavelength is close to the diameter of the waveguides.