Based on the structure health monitoring of civil engineering structure such as bridges, dams, high-rise building, the fiber Bragg grating sensor is used to achieve the real-time monitoring and diagnosis of structural performance, in order to discovery the damage and to evaluate the safety of structure. Fiber-optical grating sensing based on flextensional member is proposed. The measuring of pressure, strain and acceleration can be realized. The strain of camber beam belly is analysed theoretically and verified experimentally. The strain of the camber beam belly is proportional to the pressure and acceleration in the vertical direction. Its biggest advantage is small size under the same sensitivity. The transverse dimensions is limited in well and the longitudinal acceleration needs to be measured, so beam based sensor structure are not likely to be used. Under the condition of measuring longitudinal acceleration sensor structure, beam pumping are not likely to be used. This new type of flextensional member elastic sensitive structure can serve as elastic element for the design of fiber bragg grating strain, weighing and pressure, and acceleration sensor.