Two types of manganese dioxides with various morphology are prepared by hydrothermal method based on the redox reaction between Mn(NO3)2 and (NH4)2S2O8 under different hydrothermal conditions. The prepared MnO2 are characterized by XRD, SEM, TEM and H2-TPR techniques, and tested for the catalytic combustion of dimethyl ether(DME). The results show that the concentration of reactants and the reaction temperature mainly influence the morphology of MnO2. With the concentration of Mn(NO3)2 rise to 0.2 mol/L, the shape of α-MnO2 change from nanorod to urchin; Improving the concentration of (NH4)2S2O8 above 0.1 mol/L favors for the formation of uniform urchin shape of α-MnO2; The sulfur acid affect greatly the crystal structure of MnO2 , and enhancing the concentration over 0.61 mol/L can make the MnO2 evolving from γ phase to α phase. Compared with α-MnO2, the urchin-like γ-MnO2 displays better activity in the DME combustion reaction with a T10 of 145℃ and a T90 of 236℃, which is related with the H2-TPR result.