Manganese and cerium oxides are extensively used for selective catalytic reduction (SCR) in denitrification reaction due to their high redox ability and excellent low-temperature SCR activities. However, these catalysts still face problems such as easy aggregation of active components and low specific surface area, which restricts the enhancement of catalytic activity. Here, graphene based SiO₂ nanocomposites (G@SiO₂) with mesoporous structure was used as the template to prepare series of graphene based mesoporous manganese-cerium oxides (G@MnO_x-CeO₂) catalysts by hydrothermal method. The obtained catalysts were investigated for selective catalytic reduction (SCR) of NO at low temperature (100-300 ℃). The results indicate that G@MnO_x-CeO₂ catalyst exhibits better SCR activity than graphene based cerium oxides (G@CeO₂). With the mass ratio of Mn and Ce to G@SiO₂ of 0.35 and 0.90, respectively, the G@Mn(0.35)Ce(0.9) catalyst shows the best NO removal activity with the maximum conversion of 80% at 220 ℃. It is found that the addition of appropriate amount of MnO_x increases specific surface area and pore volume but decreases crystallinity of the catalyst G@MnO_x-CeO₂. Furthermore, MnO_x and CeO₂ are uniformly distributed on the surface of graphene sheets in the form of nanoparticles. In addition, partial replaced Ce atoms is actually doped with Mn atoms into the structure of CeO₂ to form MnO_x-CeO₂ solid solution, resulting in higher percentage of Mn³⁺and Mn⁴⁺ with higher valance states and Ce⁴⁺, and higher concentration of surface chemisorbed oxygen on the surface. These results contribute to higher SCR activity of the G@Mn(0.35)Ce(0.9) catalyst. This work provides promising basic data for the practical application of MnO_x-CeO₂ based catalysts in low temperature NH₃-SCR.