A hybrid plasmonic waveguide with an alternative structure is presented in this paper, which consists of a silver cylindrical nanowire coated with a low-index dielectric silica layer attached on a silicon-on-insulator (SOI) substrate with a rectangular ridge. The effects of the silver nanowire, silica-coated layer, silicon substrate layer, and the ridge’s width to thickness ratio on the modal properties have been numerically investigated based on the finite-difference time-domain method. The simulation results demonstrate that the introduction of the low-loss dielectric-coated layer and the ridge of SOI substrate can greatly increase the propagation distance while maintaining strong confinement of light. The propagation distance as long as and mode field with subwavelength confinement can be simultaneously realized at telecommunication wavelength. The proposed waveguide consisting of the silica-coated silver nanowire and the SOI ridge substrate would be a beneficial complement to the expanding family of hybrid plasmonic structures.