In this paper,a novel ultra-thin hybrid plasmonic waveguide composed of a silicon nanowire and a thin metal layer is designed.The geometry of the waveguide is much different from the traditional hybrid plasmonic waveguide such as wedge or rectangle hybrid plasmonic waveguide(HPW).With strong coupling between the silicon nanowire mode and long-range surface plasmon polariton(SPP)mode.both deep subwavelength mode confinement and low propagation loss has been achieved.