<p>A series of <i>x</i>Ce/GG catalysts (where <i>x</i> represents Ce loading amounts) was prepared using thermally modified coal gangue as the support for NH₃-SCR de-NO_<i>x</i>. Among them, the 20Ce/GG catalyst generated the best de-NO_<i>x</i> activity (exceeding 90% activity between 300–420 ℃) and superior SO₂ + H₂O resistance. Analysis revealed that Ce loading remarkably affected the physicochemical characteristics of catalysts, thereby influencing their de-NO_<i>x</i> performance. The 20Ce/GG owned the largest amount of active species and surface adsorbed oxygen, resulting in its greatest surface acidity and redox ability. Additionally, it had the highest specific surface area and the lowest crystallinity of surface active species. Finally, it followed the E-R and L–H reaction routes, with the adsorbed NH₃ reacting with gaseous NO_<i>x</i> as the dominant process.</p>