A novel fiber Bragg grating(FBG) filter was designed and realized based on analyzing basic principle of fiber grating tuning.In the filter,a single FBG is mounted between a fixed clamp and a movable one.The Bragg wavelength of the FBG is tuned by accurately monitoring the displacement of the movable clamp towards the fixed clamp.It is demonstrated that the tunable range of the filter reaches as much as 40 nm.The experimental results indicate that the tuning wavelength has a strictly conic relationship with the displacement of the movable clamp.