In order to study the imaging quality of different order mode Lamb waves, the propagation of the Lamb wave are studied by theoretical calculation and simulation experiment. It was found that the velocity shift of the high order mode Lamb wave was more sensitive to the variations of elastic coefficients than that of the low mode, and the radius of the Lamb wave was closer to the actual radius, the image quality was better than low modes. Thus high image quality could be obtained by using high modes of Lamb wave in the analysis of image.