Abstract: A subwavelength conductor gap silicon(CGS) hybrid plasma waveguide was theoretically analyzed, which consisted of a thin low-index layer sandwiched between a silver strip and a high index silicon structure. The guiding properties of surface plasmon polaritons, such as propagation length and mode field area, were investigated for different rib widths and silica gap layer thickness. As a result, an effective modal area of 0.08 m2 and the propagation length of 430 m can be achieved simultaneously. Based on which, the silicon slab based CGS waveguide can be formed by increasing the width of silicon rib, it should be noted that the structure can generate the larger effective refractive index value of 2.8 and the propagation length of 1.74 mm, moreover, it provided a more strong confinement of the optical field such as 0.025 m2 thickness SiO2 gap. In addition, more simple structure and CMOS compatible fabrication process make these conductor gap silicon plasmonic waveguide a promising candidate for realizing high integration density plasmonic circuits.