A theoretical investigation by split-step Fourier method is presented on the propagation of a femtosecond Gauss pulse in photonic crystal fibers.The effect of initial chirp on pulse compression is simulated and analyzed.It is found that compression factor,compression quality factor and peak power increase with initial chirp,while optimal fiber length decreases.If an appropriate optical fiber length is selected,efficient pulse with various central wavelength compression can be attained in photonic crystal fi...