Flexible sensors play an increasingly important role in damage detection of curved sheet-like structures in large-scale equipment. The sensor array is widely used in plate-like structures because it can collect damage information in a centralized manner. The annular array has the same sensitivity to damage in all directions of the circular array element. This design can realize the comprehensive detection of structural damage and improve the detection efficiency of structural damage. Aiming at the flexible sensor required for health monitoring of large flexible plate-like structures, an annular composite based on a flexible polydimethylsiloxane (PDMS) material and a flexible polyvinylidene difluoride (PVDF) material substrate was designed. A broadband omnidirectional interdigital transducer (IDT) was integrated into an annular IDT array to calibrate its frequency response and vibration output performance, and the sensor was applied to the structural inspection.