Based on stimulated Raman scattering theroy in optical fiber, an all-optical wavelength conversion coupler is designed. The wavelength converter was processed to achieve an equal power in each channel by cascaded optical fiber. All-optical wavelength conversion theoretical model, the design scheme and implemented method are presented. The simulations are calculatated by OptiSystem with a pump signal and 4 continuous probe signals. 4 wavelength converted continuous probe signals and analogous input-output code type are showed as the simulation result. The inceasing conversion efficiency and the growing extinction ratio are presented by the wavelength growth. The maximum conversion efficiency and extinction ratio are -34 dB and 36.68 dB respectively. The decreasing Q factor is showed with probe signal wavelength gorwth and 128.29 is the maximum Q factor value. 4 outputs signal light peak power and extinction ratio are approximately the same after cascading the optical fiber. The decreasing Q factor value is presented by cascading the optical fiber and the maximum value is 89.5455. The feasibility is verified by the scheme.