A hybrid plasmonic waveguide that consists of a semiconductor nanowire and semicirculartop metal nanoridge was proposed. Finite element method was used to numerically evaluate hybrid mode′s deep subwavelength field confinement and propagation loss etc. Simulation results reveal that mode area of 0.001 81(λ2/4) and propagation distance of 20 μm are obtained at the wavelength of 1.55 μm; the proposed waveguide has advantages of smaller mode area and longer propagation distance over other similar structures that has potential in fabrication of integrated photonic components and circuits.