A long period fiber grating bend sensor was fabricated in mismatched twin core fiber by CO2 laser irradiation. Theoretical analysis indicate that the fiber core located at the edge of the cladding greatly enhances the residual stress. Under CO2 laser exposure,the long period fiber grating experiences a high quality. Moreover, the fiber grating is sensitive to polorization property due to the asymmetrical structure, the polarization dependent loss value of the long period fiber grating is as high as 20.8dB at the resonant wavelength of 1 553.3 nm. Sensing experiment reveals that it can distinguish the orientation of the curvature by the resonant peak showing a red or blue shift. The fiber grating experiences significant sensitivities of 2.37 nm/m－1 and 1.80 nm/m－1 with the micro-bending range of 0~1.235m－1 for +y and －y axis directions. The proposed sensor has the advantages of simple structure and high sensitivity. It could be used in struction health monitoring applications including roads and bridges.