We investigate power-dependent phase-matched four-wave mixing FWM in wavelength division multiplexing transmission lines, in which positive and negative dispersion fibers are alternately arranged to manage the dispersion and the dispersion slope. The FWM effect shows power-independent phase matching when the channel power is low. However, it is power dependent at high power. The maximum FWM conversion efficiency is shifted away from the zero channel space in the case of powerdependent phase matching. Optimization of the dispersion system for suppression of the FWM effect is determined.