针对采用表面波检测工件表面、近表面缺陷(d＜2λ)时无法测定缺陷深度这一问题，通过理论计算不同距离处具有一定长度、不同深度的人工模拟裂纹缺陷反射回波与工件棱边(可视为无限长、无限深裂纹)反射回波之间的波幅差Δ值，并与实际检测得出的数据进行线性拟合。试验结果表明，理论计算值与实际检测值吻合情况良好，因此可以通过理论计算作出相应的DGS曲线来对表面及近表面缺陷进行相应的当量深度估算，弥补了该领域的空白。

To solve the problem that the depth of surface and near-surface defects(d＜2λ) can not be measured. Through the theoretical calculation, the value of the difference amplitude between the crack defects of artificial simulation at different distances with a certain length and the edge of workpiece was obtained, and the later one could be considered as infinitely length and infinitely depth. Comparisons were made with the actual testing data after linear fitting it. The result showed that the theoretical value was nearly the same with that obtained from the experiment. So it could make the corresponding equivalent depth analysis with DGS curves which were drawn by theoretical calculation for the surface and near surface defects. It filled a blank of this field.