Detecting defects in cavity structures is a challenging task in the field of nondestructive testing and the defects are often missed in the testing process. Creeping wave is a type of compressional wave propagating along curved surface

which is sensitive to surface and near-surface defects. Creeping wave detection provides a possibility to recognize defects in the cavity structures. Consequently

we analyzed the dispersion and attenuation characteristics of creeping wave by solving dispersion equations. A numerical model based on FEM was developed to simulate the interaction of the electromagnetic ultrasonic creeping wave with the cavity crack

and the detection ability of creeping wave to internal defect was researched. Three common crack defects were analyzed in the structure of cavity. An electromagnetic ultrasonic creeping wave detection experimental system was successfully applied to validate the observed phenomena in the simulation results. The simulation and test results show that the creeping wave can not only identify the defects that are difficult to detect in the cavity

but also locate the defects

which provides a new method for the cavity structure defect（such as bolt holes） in high voltage electrical equipment.