Jajte introduced the operator semi-stable distributions on R n in [2] and proved an important fact: A full distribution is operator semi-stable, if and only if, there exist a number c 0 < c < 1 , a vector h ∈ R n , and a nonsingular linear operator B in R n such that the formula c = B * h holds. In this paper, we make use of the eigenvalue of the matrix B to give a necessary and sufficient condition for x ≤1 x r M dx < , where M is the Lévy measure of . Also, we use the symmetric group of to characterize the operators B in (1).