CNTs produced from chemical vapor deposition usually accompany with various impurities such as carbonaceous species and metal residues. In this work, the influence of graphitization and oxidation on the catalytic activity of the CNTs is investigated by using of acrolein oxidation reaction (ACR) as a probe reaction. The results suggest that the presence of amorphous carbon is detrimental to the catalytic performance because of the loss and reproducing from those of unstable functional groups on the surface. Kinetic measurements also reveal that the coverage of amorphous carbon attached on the carbon surface hampers the in-situ formation of active oxygen groups expoxy/lactone, reactant diffusion and ACR reaction. Our work provides valuable information on the design of modified carbon materials with more excellent properties and gives an alternative way for oxidation of aldehyde from an industrial point of view.