According to the study for the automatic measurement and analysis of the asphalt mixture system, this paper makes a thorough discussion to the algorithm of digital image seg mentation, and it offers selection methods of various thresholds. Moreover, it uses characteris tics in the intensity histogram of the asphalt mixture, to analyze and compare the actual pro cessing results of various algorithms. It provides the reliable basis for extracting the following characteristic value and improving the calculation of the parameters of the aggregate particle. Meanwhile, it plays an important role in improving the measure accuracy of the whole detection system.