Abstract: In order to investigate the feasibility of preparing Mn-Cr spinel-type catalysts by different methods, MnCr₂O₄ was prepared by hydrothermal, precipitation and sol-gel methods, respectively. The optimal preparation conditions were determined, and the de-NO_x efficiency and N₂ selectivity were studied. In addition, the phase compositions of the catalysts obtained were compared, and the structure-activity relationship of the catalysts was explored and analyzed. The results show that the MnCr₂O₄ catalyst prepared by the sol-gel method demonstrates pure spinel phase and exhibits the best de-NO_x performance. De-NO_x efficiency of the catalyst prepared by the sol-gel method was over 90% within 169-341 ℃ under gas hourly space velocity of 60 000 h^-1. Compared with hydrothermal and precipitation methods, the best SCR performance of the MnCr₂O₄ catalyst from the sol-gel method can be attributed to its high abundant of Mn⁴⁺, Cr⁵⁺, and O_α, the largest acid sites, and the strongest reducibility.