A theoretical investigation with the method of split-step Fourier is presented on nonlinear propagation of a femtosecond laser pulse in a photonic crystal fiber.The impact of self-phase modulation (SPM) and intrapulse stimulated Raman scattering(ISRS) and selfsteepening(SS) and group velocity dispersion and third-order dispersion (TOD) and fourth-order dispersion (FOD) on pulse shape and spectrum of the Width is simulated and analyzed.The numerical results show that the red-shifted wavelength and smoothing of spectrum is strongly dependent on the ISRS and TOD and FOD in the abnormal dispersion region.The high-order soliton of fissile and spectrum of asymmetric are found to be related to the self-steepening.