A theoretical model of clock recovery based on SOA fiber laser is presented, through which a complete numerical analysis about the clock characteristics at 40Gbit/s rate is given, which is an effective guide for experiment and necessary to optimize the system performance. The crucial parameters that determine the pulse width, energy and frequency chirp of the recovered clock pulses are investigated, including the pulse width and energy of the external data signals, the small signal gain and carrier lifetime of SOA, and the cavity loss. Injection mode-locked SOA fiber laser is not only suitable for bit clock recovery but also for frame clock recovery. A frame clock recovery scheme based on SOA is proposed, which requires the data packet to have a fixed header marker to generate a stronger frame clock frequency component. Simulation results show a high-quality frame clock can be obtained using this scheme. In experiment, bit clock recovery is realized at bit rates up to 20Gb/s using injection mode-locked SOA fiber laser. In addition, 2.5GHz frame clock is also extracted from 8x2.5Gb/s and 16x2.5Gb/s OTDM signals. The recovered clock pulses are wavelength tunable and very stable, which can be used for high-speed all-optical signal processing.