Based on the surface plasmon physical mechanism,a 2-dimension sub-wavelength channel structure with high confinement factor was presented,Whose size was both sub-wavelengh in 2-dimension,and the power was mainly confined in the core section.Power confinement factor was as high as 98.5 percent when the core cross section was 200 nm×800 nm.,and the lateral mode size was almost equal to the width of the core section.If the height of the metal wall was larger than the cut-off height,the lateral mode size could be deep subwavelength.The Ex field component of the fundamental mode was confined in the core section,the Ey field component only exists at the four angles formed by the metal and dielectric,being antisymmetric with respect to x and y axes.