Homogeneous distribution of Mn-Fe oxides (xMn1Fe) with different Mn/Fe ratios was synthesized by a hydrolysis-driven redox method, and their catalytic activities in HCHO oxidation were investigated. The results showed that HCHO conversion was significantly improved after doping iron due to the synergistic effect between manganese and iron. The 5Mn1Fe catalyst exhibits excellent catalytic activity, achieving >90% HCHO conversion at 80 °C and nearly 100% conversion at 100 °C. The physicochemical properties of catalysts were characterized by BET, XRD, H2-TPR, O2-TPD, and XPS techniques. Experimental results revealed that the introduction of Fe into MnO x resulted in a large surface area, a high ratio of Mn4+, abundant lattice oxygen species and oxygen vacancy, and uniform distribution of Mn and Fe, thus facilitating the oxidation of HCHO to CO2 and H2O.