Mn-La catalysts were prepared by solid-state reaction (SSR) and co-precipitation methods (CPM). The effects of preparation methods on denitration and SO₂/H₂O resistance of the catalysts were investigated. The structure and physicochemical properties of the catalysts were characterized by XRD, BET, H₂-TPR, NH₃-TPD and XPS. The results show that La doping decreases the crystallinity of MnO_x and increases the specific surface area and pore volume of MnO_x. The bond cooperation of Mn-O-La promotes the dispersion of Mn on the catalyst surface, while the highly dispersed Mn are easier to be reduced. The reduction temperature of the catalyst moves to lower temperature, and the redox ability is improved. After La doping, the amount of Br?nsted acid and total acid increase on the catalyst surface, and the concentration of Mn⁴⁺ and the surface chemisorption oxygen also increase. Therefore, La doping is beneficial to the denitration activity of the catalyst. The results of reaction evaluation show that MnLa-CPM catalyst exhibits the best denitration efficiency, which is close to 100% at 80 °C. In the presence of H₂O and SO₂, the denitration efficiency of MnLa-CPM catalyst can still reach 80%, showing good SO₂/H₂O resistance performance.