We present a transverse load sensor based on in-line Mach-Zehnder in terferometer (MZI).The sensor head is formed by a long period fiber grating (LPG) and bowknot-type (BTT) tape r structure through fusion splicing.With the increase of transverse load on the LPG,the couple efficiency between the core mode and the cladding mode of LPG changes,which further brings about a change of the interference fringe visi bility.The experimental results show that the structure with a 3cm-long LPG has the sensitivity of －10.476dB/(N/mm) for the wavelengths of 1562nm,which is about 2times higher than that of the curre nt similar existing transverse load sensor.The sensor has high sensitivity,low cost and simple structure,which can be widel y applied in industry.