Abstract: In order to better detect the delamination defects in carbon fiber reinforced polymer matrix composites (CFRP), especially near-surface defects, straight probes, delay block probes, water immersion point focus probes and dual crystal probes are used to perform the CFRP laminate A-scan, B-scan and C-scan imaging detection contrast test. The test results show that the four detection techniques can effectively detect the delamination defects in the 2.5 mm thick contrast test block, and can effectively identify the defects between the 0.4 mm depth near the surface and the 2~3 plies on the far surface; straight probes, delay block probes and water immersion focus probes will form interface waves during detection, which will interfere with the imaging of near-surface defects, while dual-crystal probes have small blind areas, accurate quantification, and no interference from interfacial waves, which can detect near-surface defects of CFRP laminates with high rate and more reliable detection.