In quantifying the morphological features of aggregate, X-ray computed tomography (CT) is one of the most popularly used approaches for capturing aggregate images that is considered accurate and reliable. In this study, however, a three-dimensional (3D) optical scanner was also employed to characterize aggregate morphology in addition to X-ray CT. The major objective is to validate the accuracy of the optical scanner–based image analysis method through a comparative study of the optical scanning and X-ray CT results. Four types of aggregate particles were selected, and their aggregate images were obtained through those two methods. Second, the scanned aggregate images were saved in STereoLithography (STL) files and analyzed. Then the differences in the morphological features of aggregate obtained from these two methods were quantified and evaluated. Through this study, it was found that even though there were relatively large differences in special aggregate particles (flat or elongated aggregates), the 3D optical scanner was comparable with the X-ray CT in the overall quality of the morphological characteristics of aggregate. Furthermore, differences between the two scanning technologies are dependent on particle shape and surface features. Aggregate particles with sharp angles or rich surface features may induce larger differences.