In order to solve the problem of low sensitivity in low-frequency vibration monitoring of bridges,a low-frequency and high-sensitivity fiber Bragg grating (FBG) acceleration sensor is proposed based on an equal strength cantilever beam.Twelve groups of FBG acceleration sensors are designed with the thickness of the cantilever beam and the weight of the mass block as the main parameters.The amplitude-frequency characteristics,sensitivity,and transverse anti-interference tests of the sensors are carried out by a vibration generator.And a set of sensors suitable for monitoring bridge vibration are obtained.The natural frequency of the sensor is 49 Hz,the operating band is 0—34 Hz,the sensitivity is up to 664.53 pm/g,the linearity is 99.9%,and the lateral anti-interference ability is strong.A novel and effective monitoring method is provided for bridge vibration by theoretical derivation and experimental verification.