The tri axial characteristic, roundness and sphericity of limestone and waste iron tailing rock coarse aggregates were determined by Image Pro Plus(IPP) software. The statistical analyses on the isometric ratio, roundness and sphericity of limestone and waste iron tailing rock coarse aggregates with different particle sizes were done by Statistical Product and Service Solutions(SPSS) software, and the relationships among the three parameters were established. The results indicate that the isometric ratio, roundness and sphericity of limestone and waste iron tailing rock coarse aggregates with different particle sizes are all in accordance with the normal distribution approximately, and the three parameters have good consistency in characterizing the particle shapes of different type or different sized coarse aggregates. Furthermore, the relationship among the sphericity and isometric ratio and roundness of coarse aggregate fits in a highly significant binary linear regression equation.