Abstract: This paper describes a laser ultrasound imaging technology based on velocity analysis.Scanning the Al surface in two dimensions, simultaneously the ultrasonic wave was simultaneously received by the transducer on the other side of the scanning area, and detailed analysis of the ultrasonic propagation velocity image at the different positions within defect and no-defect was carried out. The experimental results show that the laser ultrasound imaging technology based on velocity analysis can effectively detect the position of the defect, which provides the basis for the quantitative defect detection.