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In this paper¡Awe use both beam propagation method and BPM_CAD to analysis the characteristics of nonlinear optical waveguide structures. The refractive index of optical waveguide medium changes with field intensity called nonlinear optical waveguide. We use Mode Theory to solve three layers optical waveguide. There are nonlinear cladding, substrate layers and linear film. Not only find the disperson relation curve, but also observe the affections of the input power to field distribution. With the help of this, we propose a general math method to analysis symmetric muti-layer optical waveguide with periodic index that both cladding and substrate are nonlinear. According to the nonlinear dispersion relation we consider both the affections of the input power to refractive index in the film and space soliton at nonlinear interface. We propose a optical coupler and feed-back optical switch. And also, we analysis 2¡Ñ3 branches optical waveguides by changing their media to nonlinear media. According to the result, we find that they have both logic function and optical switch.