let d be a symmetric 2-(121, 16, 2) design with the automorphism group of aut(d). in this paper the order of automorphism of prime order of aut(d) is studied, and some results are obtained about the number of fixed points of these automorphisms. also we will show that |aut(d)|=2p 3q 5r 7s 11t 13u, where p, q, r, s, t and u are non-negative integers such that r, s, t, u ? 1. in addition we prese...