Given the problem of the high-temperature window of CeO₂ catalyst activity, this study evaluated the catalytic properties of Ag/CeO₂ prepared by changing the preparation methods and loadings. Our experiments showed that Ag/CeO₂-IM catalysts prepared by the equal volume impregnation method could have better activity at lower temperatures. The Ag/CeO₂-IM catalyst achieves 90% NH₃ conversion at 200 °C, and the main reason is that the Ag/CeO₂-IM catalyst has more vital redox properties, and the NH₃ catalytic oxidation temperature is lower. However, its high-temperature N₂ selectivity still needs to be improved and may be related to the less acidic sites on the catalyst surface. On both catalyst surfaces, the i-SCR mechanism governs the NH₃-SCO reaction.