A high sensitivity curvature sensor based on thin core fiber (TCF) and Mach-Zehnder interferometer (MZI) structure is proposed.The sensor head is fabricated by a c ore-offset splicing of a TCF in two SMFs.As the MZI becomes bent,the interference between the core and clad ding modes is enhanced due to core-offset.The optical fiber curvature sensor can be realized by detec ting the changes of interference intensities to the variation of curvature.To improve the accuracy of the curvature calibration,a curvature corrected model is obtained by using the fiber curve catenary method. The experimental results show that the curvature sensitivity of 142.28dB/m－1 is obtained in the c urvature range of 9.15m－1 to 11.02m－1. This high sensitivity,low coat and intensity demodulation fiber curvature senso r has broad application prospects.