A tunable bandpass microwave photonic filter (MPF) based on multi-wavelength fiber laser (MWFL) which is used as the light source is proposed and demonstrated. The combination of the phase modulator and the dispersion devices convert the phase modulation to intensity modulation in the ordinary single-mode fiber, and it eliminates the low-frequency resonant peak thus a new bandpass filter is realized. By using one of the birefringent fiber loop mirror output windows for the apodization of the multi-wavelength signal, the main lobe to sidelobe suppression ratio of the MPF is raised about 11 dB. The wavelength interval of the MWFL can be adjusted by tuning the polarization controllers (PC) in it. The time delay between adjacent wavelengths is changed when the laser signal passes through the ordinary single-mode fiber because of the dispersion in it thus the central frequency of the band pass MPF is tuned within 7.66 GHz.