基于尾纤端面镀金属反膜的单根长周期光纤光栅，提出了一种包层部分腐蚀的长周期光纤光栅迈克耳孙干涉仪结构，提高了长周期光纤光栅(LPFG)的灵敏度。应用干涉原理，得出了长周期光纤光栅迈克耳孙干涉仪干涉波峰随外界环境折射率的变化关系。并从实验上对腐蚀前的长周期光纤光栅迈克耳孙干涉仪和带腐蚀结构的长周期光纤光栅迈克耳孙干涉仪的折射率传感灵敏度进行对比。结果表明，包层部分腐蚀的长周期光纤光栅迈克耳孙干涉仪反射谱中的干涉峰值对折射率传感的灵敏度得到了显著的提高，对于折射率为1.333 和1.352 的液体，干涉峰值的移动量从0.9 nm 增加到3.4 nm。

Based on a single long period fiber grating (LPFG) with optical fiber pigtail coated with highreflective film, a LPFG Michelson interferometer with partly etched fiber cladding LPFG is designed. It improves the LPFG sensitivity. By applying interference principle, the change of interference peaks along with environment refractive index is obtained. The refractive index sensitivity of no etched LPFG Michelson interferometer is compared with that of the etched LPFG Michelson interferometer, results show that the change of the refractive index sensitivity is significantly improved. The peak wavelength of interferometer shifts from 0.9 nm to 3.4 nm when liquid refractive index is 1.333 and 1.352.