Lithium–silicon-powder waste, combined with ferromanganese ore (MnFe/Z), shows great promise as a cost-effective low-temperature NH3–SCR catalyst for NOxemission control. However, the MnFe/Z catalyst’s low sulfur tolerance limits its applications. A natural ilmenite (NI)-doped catalyst (NIx–MnFe/Z) was carefully studied and optimized to address this deficiency. The results revealed that natural ilmenite doping enhanced MnFe/Z’s antisulfur performance without negatively affecting catalytic activity in the low-temperature range (125–200 °C). The optimized NI3–MnFe/Z had the best catalytic activity, maintaining 96.5% NO conversion after 6 h under 50 ppm of SO2at 175 °C. The introduced NI suppressed the electron transfer from Mn4+and Fe3+to SO2and reduced sulfate formation, effectively protecting the active sites from SO2poisoning. NI addition protected the redox properties of Mn and Fe and the acidity of the catalyst; the NI3–MnFe/Z catalyst broke the SO2poisoning obstacles in low-temperature NH3–SCR toward future application for efficient NO elimination from industrial flue gas.