In this paper, a new optical transmission model was investigated and developed in order to improve the performance of Wavelength Division Multiplexing optical transmission systems. For this purpose, an efficient theoretical method combining a Fiber Bragg Grating (FBG) and Erbium Doped Fiber Amplifier (EDFA) was implemented. Enhancements on the transmitted signal amplitudes with important compensation of the chromatic dispersions and large reduction on the nonlinear effects were obtained. The reflectivity peak, the full width at half maximum bandwidth, and the side lobe level have been studied in depth to demonstrate the efficiency of the proposed method. To apply the new method, we considered a complicated system of 16-channel wavelengths, where the split-step fourier method was used to solve the nonlinear Schrödinger equations, and the transfer matrix method was applied to describe the coupled mode equations. The wavelengths corresponding to different values of reflectivity peaks calculated previously in the FBG outputs section were injected as EDFA inputs to determine the output power and the gain of the new transmission system. All results are analyzed using Matlab program.