Corrosion damage exists extensively in material structures in the industries, such as national defense and transportation, which threatens the safety and reliability of the structure seriously. Therefore, it is of great significance to monitor corrosion damage in materials. In this paper, based on the theory of laser ultrasound, an automatic laser scanner detection system was designed and developed. The laser scanning experiments were carried out on the corrosion damage in the aluminum plate through this system, and the relationship among the Lamb wave energy, amplitude and corrosion was analyzed. The damage area was visualized with the maximum amplitude according to the principle of “elastic wave energy flow method”. Finally, the amplitude integral ratio method was proposed, which can be used to evaluate the degree of corrosion damage. The proposed method can realize the rapid detection and evaluation of corrosion defects with the detection results being visualized, showing a great potential in application.