Abstract: To investigate the causes of large-area ultrasonic signal anomalies in helicopter composite chair basin laminates, research on the design and fabrication of comparative test blocks for laminates was conducted. Through analysis and summarization of ultrasonic testing signals from prefabricated defect comparative test blocks, the characteristic differences in ultrasonic signals corresponding to two types of defects, delamination and resin richness, were obtained. The experimental results showed that there were certain differences in the bottom wave, defect wave, clutter, and C-scan images of ultrasonic testing for different defects. Through analysis, accurate determination of delamination and resin richness defects could be achieved, and precise localization and quantification of defects could be realized. This determination method could be applied to daily inspection work of chair basin laminates.