Promotion of nitrogen-doped graphene (NG) by incorporation of ferric oxide (NG-Fe2O3) is found to strongly enhance the activity in the catalytic oxidization of aldehyde to synthesize carboxylic acid with O-2. The composite NG-Fe2O3 catalysts can be fabricated by a facile one-pot hydrothermal method. The characterization results of the composite catalysts have revealed that the Fe2O3 nanoparticles (NPs) with sizes of 40-90 nm are not only on both sides of NG sheets but also tightly enwrapped by the graphene layers. In comparison to NG and Fe2O3 NPs, synergistic adsorption that confirmed by DFT studies has been created on the NG-Fe2O3 composites, where both NG and Fe2O3 are proposed to be involved in the adsorptive interaction. The synergistic adsorption can lead to strengthen O-2 molecule adsorption of NG and weaken O-2 molecule adsorption of Fe2O3 NPs. More importantly, the NG-Fe2O3 composite is found to considerably facilitate the longest elongation of O-O bonds and contribute to the striking enhancement of the catalytic performance. The highly active NG-Fe2O3 composite shows wide scope for catalysis of oxidation of aldehydes to carboxylic acids and good stability for recycle six times.