A novel and simple chirp tuning device of fiber Bragg grating (FBG) is proposed, which possesses a “C” shape and consists of a straight beam and two half-round arches. A linear strain field is induced over the straight beam by applying stress on the arches. As a result, the uniform FBG bonded on the surface of the beam is converted to a linearly chirped fiber grating. The bandwidth of the FBG is tuned linearly by applied stress with the sensitivity up to 0.34 nm/N and a linearity of 0.9982. In the experiment, a chirp bandwidth of about 7 nm can be obtained with the stress of 20 N. Additionally, the reflective spectra are quite flat. The experimental results are in good agreement with the analyses. Due to the characteristic of the bandwidth immunity to environmental temperature variation and large tunable range of bandwidth, the device can be applied in fields such as measurement of stress (strain, curvature, etc.), fiber laser, chromatic dispersion compensation.