Abstract: For high accuracy of curvature measurement, a curvature sensor with polarization-maintaining photonic crystal fiber (PM-PCF) was proposed based on Mach-Zehnder interferometer structure. The fiber structure of the sensor head was formed by single-mode, up-taper, PM-PCF, multimode and single-mode fibers. Dislocation fusion was done between multimode and single mode fibers. After theoretical analysis and experiment verification, the linear relationship between resonance wavelength shift and curvature change in the curvature range of 0.04582m-1~0.054776m-1 and 0.054776m-1~0.06929m-1 was proved. The results show that the curvature sensor can be implied in health monitoring when the sensitivities of the sensor are 93.95nm/m-1 and 30.89nm/m-1.