Raw powder of iron ore tailing, the catalyst prepared by impregnation approach and the modified catalyst loaded Ag+ were investigated for catalytic oxidation of formaldehyde. Prepared materials were characterized by XRD, XRF and BET surface area. Experiments of catalytic activity were carried out in an electrically heated fixed-bed reactor in which 1.0g of catalyst mixed fully with 10g quartz sand was added. 200ppm of formaldehyde gas was introduced into the reactor at a space velocity of 30,000ml/g·h. Effects of reaction temperature and calcination temperature were considered. The results show that formaldehyde catalytic efficiencies of all materials increase with the increase of reaction temperature. Furthermore, the catalytic efficiency was enhanced when Ag+ loaded on the support. Physical properties of raw powder are unsatisfied, but 67% of formaldehyde catalytic efficiency was obtained at the reaction temperature of 100°C which is far higher than that of other prepared catalysts.