Aggregate particle size was measured by the minimum bounding box （MBB） method and compared with that calculated by the equal volume sphere （EVS） method. The results of these two methods on the internal structure of meso-concrete were analyzed. The results show that the aggregate particle size calculated by MBB method is close to that measured by sieving method in the laboratory test. Compared with the MBB method， the EVS method tends to underestimate the particle sizes of spherical， blade and disc types of aggregates， and the percentage of underestimated aggregates is in descending order as spherical， blade and disc types while that of the particles of rode type was overestimated. The influence of the particle size calculation method on the internal structure of meso- concrete shows some differences with respect to the type of aggregate shape.