The catalysts with low-temperature activity and high sulfur resistance are expected in the denitration application. To obtain an efficient and eco-friendly catalyst for NO_x abatement, phosphotungstic acid (HPW) promoted Mn-Fe bimetal oxide composites were constructed by colloidal solution combustion synthesis followed by the impregnation method. Their catalytic mechanism and activity at low temperature analyzed in detail by XRD, BET, SEM, XPS, H₂-TPR, NH₃-TPD and in situ DRIFTS characterizations. The results show that the large surface area and uniform mesoporous of Mn-Fe oxide contributed to the dispersion of HPW nanoparticles. The highly dispersed HPW can regulate the surface acidity and redox property of the catalyst. The Mn_0.25Fe_0.75-HPW50 compound combined the redox property of mesoporous Mn-Fe oxide and the acidic advantage of HPW showed a wider operating temperature window (125-400 °C, NO_x conversion >94%) with higher N₂ selectivity and SO₂ resistance. Langmuir-Hinshelwood (L-H) and Eley-Rideal mechanisms (E-R) coexist in the SCR reaction. This work can provide a strategy for designing composite materials with low-temperature activity and high sulfur resistance. The developed porous HPW-promoted Mn-Fe oxide would be a promising catalyst candidate for NO_x removal.