Serious up-conversion process (UCPE) of Er 3+ in Er 3+ /Yb 3+ codoped tellurite glass is one of the big challenges impeding Er 3+ doped tellurite fiber amplifier towards full commercialization, though its gain bandwidth is much wider than Er 3+ doped silica fiber amplifier. For solving or suppressing UCPE, it has been proposed to better introduce a third foreign ion with proper layout of energy level into this system, and thus, modulate energy transfer between them. Three rare earth ions, RE 3+ =Ce 3+ , Dy 3+ , and Tb 3+ , are selected in this paper, and it turns out that three of them can efficiently reduce the transition probability of UCPE, and Ce 3+ rather than Dy 3+ and Tb 3+ can at the same time enhance the 1.53μm emission of Er 3+ originating 4 I 13/2 → 4 I 15/2 . The underlying mechanism will be discussed based on both experimental and theoretical results.