The temporal and spectral characteristics of output pulse for an optical pulse cleaner under the input pulses with initial chirps and different shapes were analyzed, by solving the coupling mode equations, which ignored coherent coupling part and neglected chromatic dispersion of the fiber. It was concluded that, the Gauss pulse′s temporal shape was narrowed seriously after the pulse cleaner, and the initial chirps and the energy transmittance were independent of the initial chirps, but the output spectrum were quite different with the initial chirps. When the temporal shape of the input pulse was square, the output pulse′s temporal shape and the spectral shape were both changed slightly but the energy transmittance was highly enhanced.