A novel high sensitivity fiber optic bending sensor based on Michelson interferometry was developed. The sensing probe utilizes a fiber ribbon affixed onto an elastic structure to generate interference signals as a function of curvature. Further a micro-cavity filled with refractive index matching liquid was added to the optical path length and modulated in audio frequency to modify interference signal, which was demodulated using phase generated signal carrier technology to obtain a highly sensitive detection of curvature change. Experimental measurement of prototype shows that the fiber optic bending sensor can achieve a sensitivity of 43.96 rad/m－1 and a high resolution of 0.004 m－1.