The electric dipole radiative transition probabilities between levels nil1-nklk(ni≤5,nk≤15) for Na-like Fe have been calculated with multiconfiguration Dirac-Fock framework. We have confirmed the new regularity which has been found recently: the transition probability is just inversely proportional to the 3rd power of the principal quantum number n of upper level for a Eydberg series of spectrum lines when n is large enough.