Strain characteristic of a special hollow aluminium alloy cantilever were analyzed.The fibre Bragg grating(FBG) is sticked to the thin arm of the cantilever and its stress response is observed through OSA when adding load to the free end of the cantilever.The result show that the wavelength of FBG shifts about 0.215 nm when the load is 200 g;and when the cantilever is solid,the wavelength shifts only 0.019 nm.It can be conclude that enhanced-stress ensitivity can be reached through this special structure when using elastic material to coat fibre grating.