Abstract: In this paper, taking into account both the selfphasemodulation (SPM) and the lowest and second order group velocity dispersion (GVD), the propagation equations of ultrashort pulses is given through numerical analysis. The influence of input intensity on ultrashort pulses in Fibonacci superlattice is analyzed. The calculations show that the input intensity cause broadening in the spectrum and set a limit to effective length of superlattice, which is an important factor for frequency conversion.