In this paper, the definition of the 2-tuples distribution matrix is proposed, and some properties of 2-tuples distribution matrix are demonstrated. Based on these results, we introduce a new method to construct optimal orthogonal arrays OA λ (k, 2) having a row that is repeated m = ā times. A class of optimal orthogonal arrays OA λ (k, 2) having a row that is repeated m = ā times are constructed with the help of the 2-tuples distribution matrix of the orbit O k (x), where λ = 1 + 2 + • • • + ā, ā = k−1 2 and k is an odd prime.