Guided by improving the sensitivity of fiber Bragg grating (FBG) acceleration sensors,the sensitivity enhancement mechanism model is theoretically studied,and evaluation criteria is established for optimization and comprehensive performance.First of all,according to the working mechanism of inertial devices,a new general physical model of FBG acceleration sensor is established,the sensitive structure of the sensor and the design method of FBG are discussed and analyzed,and the response mechanism of its sensitivity is studied.Secondly,we analyze the influence of the inertial mass,the length of the encapsulated fiber,the stiffness of the sensitive structure and the Young′s modulus of the fiber on the sensitivity,and explore the threshold edge conditions of the stiffness of the sensitive structure to achieve high sensitivity.Finally,the concept of the "figure of merit" of the FBG acceleration sensor is proposed,combined with the threshold conditions of the sensor′s physical parameters,we study the relationship between the figure of merit and the inertial mass and fiber length.This not only provides a reliable basis for the evaluation of the comprehensive performance of the FBG acceleration sensor,but also has important theoretical guiding significance and practical application value for the design and optimization of the sensor.