This paper proposed and experimentally demonstrated an all-fiber tunable and programmable bandpass filter using a linearly chirped fiber Bragg grating (CFBG). The center wavelength and spacing of the transmission peaks could be independently tuned via computer. The tunable range is about 18 nm. With this filter we demonstrated a tunable fiber ring laser which has an output power of about - 7 dBm, full-width at halfmaximum linewidth of ~0.017 nm which is limited by the resolution of the optical spectrum analyzer (OSA). Furthermore, a spacing tunable dual-wavelength fiber laser was achieved with the same setup. This all-fiber laser features advantages like simple structure, low cost, flexible and digital tuning capability.