A narrow single pass band tunable microwave photonic filter (MPF) is designed and experimentally demonstrated based on the theory of wavelength-selective amplification of Fabry-Perot (F-P) laser with optical injection. Through changing the injection locking parameters, we investigate the influences of injection locking parameters on the the central frequency, insertion loss, and out-of-band suppression ratio, and the relationship between the wavelength power amplification and the cavity mode red-shift. The experimental results show that, when the injection power ratio, detuning frequencies of the master slave lasers and bias current are properly adjusted, the out-of-band suppression ratio of MPF is 27.9 dB, the 3 dB passband is 275 MHz and the frequency of MPF can be tuned from 9 GHz to 32 GHz. The proposed structure is useful for applications such as filters frequency selection and optic-electric oscillation, where require high frequency and wideband tunability.