To address the performance degradation caused by the four-wave mixing (FWM) effect in dense wavelength division multiplexing (DWDM) systems, a method for suppressing the FWM effect is proposed. This method begins by comparing and analyzing three dispersion compensation schemes in optical networks with different data rates, identifying the separated dispersion compensation scheme as the optimal approach. The impact of the FWM effect is then evaluated in both 8-channel and 16-channel communication systems by separating dispersion compensation and gain. After multiple optimization steps, pre-chirping is applied to further suppress the FWM effect. The system performance is analyzed through numerical calculations of the channel bit error rate (BER). The results demonstrate that in both 8-channel and 16-channel systems, the FWM effect in the optical fiber is effectively suppressed as the number of dispersion and gain separations increases. With pre-chirping, the FWM effect is further reduced, achieving minimum channel BERs of 5.08×10^-19 and 8.77×10^-17, respectively. This study provides valuable insights and guidance for the development of next-generation high-capacity optical fiber communication systems.