Two novel passive tunable photonic microwave filters based on fiber loop and chirped fibre Bragg gratings(CFBGs) are presented,where the filter response can be easily tuned by adjusting the wavelength of the input light.The required free spectral range(FSR) of the filter can be designed by carefully controlling the written positions of the CFBGs in the fiber loop.The potential and feasibility of the proposed two filtering structures have been demonstrated in the laboratory.The proposed tunable filters have potential applications in microwave and millimeter-wave fiber-optic systems.