A polarization-dependent twist sensor based on an in-fiber Mach-Zeh nder interferometer is proposed. The sensor is constructed by core-offset fusion splicing of a 15-mm-long pola rization maintaining fiber (PMF) between two single mode fibers.With the increasing of the twist applied on the sensor,the intensity of the output light transmitting along the two orthogonal polarization states has changed,whi ch leads to the intensity changes of the resonance peaks in the transmission spectrum.By measuring the slow axis resonance peak intensity changes in clockwise and counterclockwise directions with the distorted angle wi thin 0－180°,the maximum sensitivity can reach 0.624dB/°·m－1,which is almost 2times of that of the existing si milar strain sensor.Due to the intensity demodulation method,the proposed sen sor has an application advantage in marked contrast compared with other twist optic fiber sensors which usually employ high-cost wavelength-shif t means.