Abstract: To address the automatic analysis issue of the aggregate grading composition, a kind of tridimensional testing method based on the structured light was presented in the paper. The 3D data of the aggregates were obtained by scanning the aggregates using the 3d monitoring system based on the structured light vision, and used the Matlab tool to reconstruct the three-dimensional surfaces of the aggregates, after that the 3d aggregates particles were segmented using the median filtering and region growing method. the aggregate volume was calculated by the differential method, and the aggregate particle size was determined by the equivalent sphere diameter, then obtained the percentage of aggregates devoted to different sieve size. At last the aggregate gradation results obtained using the proposed method was compared with the sieving method, the results showed that the measurement error was less than 5%, and the gradation curve matched very well with the sieving gradation curve which verified the effectiveness and feasibility of the system.