Sr 2 CeO 4 , pure and doped with Eu 3+ ions of different concentrations, were synthesized by polyacrylamide gel method. First principles were applied to calculate the electronic structures and band gap of Sr 2 CeO 4 . The results show that a broad emission band originating from Sr 2 CeO 4 host and Eu 3+ emission lines in blue, green, and red regions coexist. The increase in Eu 3+ concentration results in the luminescence intensity redistribution between the Sr 2 CeO 4 host and the doping ion. The energy transfer model clarifies the possible mechanisms of energy transfer from Sr 2 CeO 4 host to Eu 3+ in Sr 2 CeO 4 :Eu 3+ phosphor.