Abstract: The self-phase modulation induced optical power transfer function is analyzed in cascaded optical fiber communication system in terms of different chromatic dispersion, arbitrary fiber numbers and lengths. Computer simulations are also done. The results of simulations show that the power change of self-phase modulation (SPM) relates to fiber loss, nonlinear coefficient and modulation frequency of system and fluctuates with change of modulation frequency. The simulations are well accordance with the analytical result.