In optical wavelength-division multiplexing (WDM) systems, if the number of users are increased, the crosstalk becomes more severe due to imperfections in the optical passive networks and nonlinear effects in the optical fiber. In this research paper Stimulated Raman Scattering (SRS) and Cross Phase Modulation (XPM) are studied as the source of nonlinear degradation in the multichannel system. The crosstalk induced by SRS and XPM has been evaluated for wavelength division multiplexed networks. In SRS induced crosstalk it is observed that as the modulation frequency increases the crosstalk decreases and for XPM as the modulation frequency increases the crosstalk increases. These variations have been observed for different transmission lengths.