On a basis of crystal structure and crystal chemistry theory,according to the crystal cell parameters of cordierite and the atomic arrangement in its crystal cell,etc.,the article gave the minimum dimension of nano-cordierite corpuscle.Through calculation of the crystal cell number,atomicity,external crystal cell number and the external atomicity on the(010)crystal plane of different granularities,their characteristic were given,and the relationships between them and the specificities of nano-cordierite corpuscle were analyzed.