The all optical clock recovery scheme has certain tolerance for degraded input signal. A novel scheme including semiconductor optical amplifier (SOA), chirped fiber Bragg grating (CFBG), and stimulated Brillouin scattering (SBS) is proposed and demonstrated to recover the clock from the input degraded non-return-to-zero (NRZ) data stream. SOA and CFBG enhance the clock component, and the clock information is extracted from the clock component enhanced signal based on SBS. For different degraded signals, the signal-to-noise ratio (SNR) of the input stream is the key factor to the clock recovery. When the input SNR is worse, the noise of recovered clock spectrum is higher, and the amplitude of extracted optical clock is lower. The clock of NRZ signal could not be recovered as the clock-to-data ratio of the enhanced signal is less than -10 dB.