Based on fiber Bragg grating technology,a gravity tilt sensor is proposed to mon itor the structure tilt with high precision.When the structure is tilted,the til t Angle of gravity tilt sensor fixed on the structure will change,and the wavel ength of its internal fiber Bragg grating will change.By measuring the wavelengt h change of fiber Bragg grating,the change of structure inclination Angle is obt ained.Through the calibration test of the sensor,the results show that the sensi tivity coefficient of the sensor is 8.5 pm/,and the correlation coefficient i s above 0.99.The linearity error is 4.78%,hysteresis is 8.30%,and repeatability error is 9.34%.Good linear data are obtained,which proves that the tilt sensor h as good performance.The research results have a certain guiding significance for the design of fiber Bragg grating sensors for the measurement of tilt structure .