A fiber Bragg grating is slantingly bonded to the side of the rectangle cantilever beam, and the chirp effect of the grating would appear by adjusting the displacement of the beam's free end. The displacement sensing using the chirp effect of fiber Bragg grating under strain-gradient is demonstrated in this paper. Because the bandwidth of the grating is temperature-insensitive, the cross talk between displacement and temperature is avoided. The good linear response has been obtained.