Motivated by the low efficiency and poor accuracy of the existing techniques for measuring the depth of a pavement structure, we examine the characteristics of laser speckle and speckle measurement methods in relation to the depth of a pavement structure and propose a set of methods for the 3D measurement of such structures based on laser speckle and digital image processing. First, we analyze the relevant characteristics of laser speckle measurement, and then based on the relevant region and temporal sequence correlation, a faster digital speckle correlation method is used to establish a mathematical relationship between the 3D image and the structural depth. The erosion and dilation technique and mean optimization algorithm are proposed to eliminate the noise and burr of primeval 3D reconstruction. After this, a 3D point cloud of information on the depth of the pavement structure is obtained. Finally, through fitting, a good linear relationship was found between the texture depth obtained by the sand paving method and the system. From measurements using a laboratory calibration platform, it was found that the accuracy of measurement of our method can reach the subpixel level, and the running speed is high, meaning that it can be used for highly efficient and accurate detection of the depth of a road structure.