Abstract: Aiming at the detection of some typical defects in the secondary co-cured skin structure of aircraft, the typical characteristics of different types of defects in different positions are summarized by comparing the CIVA software theory simulation with the actual detection data. Results presented in the paper can be used as a guide for defect identification, and are convenient for inspectors to make qualitative judgment of defects more accurately. It is also verified that CIVA simulation can provide support for the formulation of detection process.