In order to get the coarse aggregate particle gradation of cement treated base course core sample dilled form the pavement, an image acquisition system is designed. The system mainly contains an Aviiva ® M2 CL line scan camera, a core sample rotation platform and a LED light source. The software are designed and implemented by using the Matrox Mil controls in the Visual Studio VB.NET. Test results show that when the camera exposure time is set to 800μs, good quality image of core sample can be obtained. In the study, the original core sample images of cement treated aggregate were improved by rescaling of each pixel, then were binarized by using adaptive threshold method. After getting the binary image, morphological operations were carried out to deal with the conglutinations of the particles. Next, characteristics of each particle, such as area, perimeter, fitting ellipse and minFeret were extracted to calculate the area passing rate of aggregate with different size. Results shows that, in this way, the gradation of coarse aggregate (>2.36mm) can be got and the method helps to get the coarse aggregate particle distribution of cement treated aggregate core sample quickly.