A tunable optoelectronic oscillator was proposed by utilizing optical injection-locking effect in a distributed feed-back laser diode. The optoelectronic oscillator loop mainly consists of an intensity modulator, a photodetector, an optical circulator, a distributed feed-back laser diode and a broad band radio frequency amplifier. In the proposed configuration, the distributed feed-back laser diode is key device. By utilizing injection locking of distributed feed-back laser diode rather than the commonly used radio-frequency band-pass filter, a high Q microwave filter is formed in optical domain, and short optoelectronic oscillator loop could be used in the proposed scheme. Thereby the effect of temperature sensitive of fiber on microwave signal stability can be declined and the system size can be reduced. Meanwhile, the central frequency of the microwave filter could be simply tuned and the tunability could be realized by tuning the wavelength and the injection power of the injection light. Theoretical analysis of the optoelectronic oscillator as well as the tunability of microwave filter was provided. Thus, experiment was done to verify the theoretical analysis. The results show that the proposed optoelectronic oscillator can produce the microwave signal with tunable range from 18.7 GHz to 21.6 GHz, and the measured phase noise at 1 kHz offset is －90 dBc/Hz.