In this paper, a novel fiber-optic micro-displacement sensor is proposed and demonstrated experimentally. A special fiber with double cladding was spliced into single mode fiber(SMF) forming the sensing structure of SMF-special fiber-SMF. Attributed to the thin thickness of inner cladding layer, a strong cladding-mode resonant spectrum iS excited and it iS very sensitive to fiber bending, which can be explored for the micro-displacement sensing applications.