Abstract: When the embedded alloy externally pressed fiber reinforced polymer（FRP） process is used to form the airfoil structure of aerospace flight carrier, the debonding defect between FRP and alloy and their internal delamination defect seriously affect the safety performance of flight carrier. In this paper, the ultrasonic penetrating C-scan detection method and defect type identification method are determined by comparing the experimental results of ultrasonic C-scan detection and ultrasonic A-scan detection of FRP embedded alloy test pieces of airfoil structure under different conditions. The experimental results show that the detection method can accurately detect the defects above 4mm×4mm, and the debonding defects and delamination defects can be accurately identified.