Abstract: The influences of preparation method, the calcined temperature and auxiliary forming reagent on the activity of the Fe Mo Co O catalyst for oxidation of methylal to formaldehyde were studied. The macrostructure, the composition of the crystal phase, the surface ion valency and concentration of the catalysts were investigated by BET, XRD and XPS techniques. The results showed that the macrostructure, the composition of the crystal phase and the catalytic activity of the catalyst are related to the calcining temperature. It was also showed that, with a suitable auxiliary forming reagent, the macrostructure of the catalyst will be improved, which is essential for high catalytic activity and heat stability.