Based on Sagnac interferometer by incorporating a segment of side-leakage photonic crystal fiber (SLPCF), a curvature sensor with high sensitivity and broad linear measurement range was proposed and demonstrated experimentally. Experimental results show that high sensitivity to curvature can be achieved by measuring group modal birefringence and wavelength shift of transmission dip when the linear side-leakage defect is in the same direction as the bending, but the linear measuring range is not large enough to cover the small curvature. When the linear side-leakage defect is in the vertical direction to the bending, the sensitivity can be as high as 10.798 nm·m-1 and the linear measurement range as wide as 0–5.03 m-1 by measuring wavelength shift of transmission. Combined with the introduction of the measurement matrix, the measurement of temperature and curvature can be realized simultaneously, which would offer a way to eliminate the perturbation of the environment temperature to the measurement values of the curvature. Under the same conditions, though the sensitivity obtained by measuring group modal birefringence is low, it can be regarded as a curvature sensor which is insensitive to temperature.