Let J be the Jacobson radical of a commutative completely primary finite ring R such that J k 6= (0) and J k+1 = (0). Then R/J ∼= GF(p r ), the finite field of p r elements, and the characteristic of R is p k where k ≥ 2 and p is some prime integer. In this paper, we determine the structures of the quotient groups 1 + J i/1 + J i+1 for every characteristic of R and 1 ≤ i ≤ k − 1.