The steady-state nonvolatile two-step, two-color holographic storage performance for both LiNbO3:Fe:Mn and LiNbO3:Fe was investigated theoretically based on the two-center model. By considering all the possible electron transfer processes between the deep-trap and the shallow-trap centers, LiNbO3:Fe was confirmed theoretically to be of bigger space-charge field and higher recording sensitivity than LiNbO3:Fe:Mn in the low intensity region.