The minimal superstring unification, assuming orbifold compactification, provides interesting and rather detailed implications on physics at low energy. The interesting feature of this model is that the masses of the spectrum are related since all of them are functions of only two parameters: the goldstino angle and the gravitino mass . This fact will help us in studying the modification of the supersymmetric magnetic moments sum rules which are very sensitive to the supersymmetry breaking. We write these rules in case of exact supersymmetry in a form close to the supersymmetric mass relations, namely , where is the anomalous magnetic moment of the spin-J particle. We show that the anomalous magnetic-moments of the W-boson and the gauginos can be written as functions of and . Then we obtain a modified version of the supersymmetric magnetic-moment sum rule in the context of the minimal superstring unification.