The invention provides a high-activity catalyst for catalyzing complete oxidation of low-concentration formaldehyde under the condition of room temperature. Said catalyst is made up by using simple easy-available metal oxide and small quantity of noble metal as raw material, its preparation method is simple. The metal oxide is used as main body of said catalyst, the noble metal component is loaded on the metal oxide. The described metal oxide can be at least one of cerium dioxide, zirconium dioxide, titanium dioxide, aluminium oxide, lanthanum sesquioxide, magnesium oxide, zinc oxide, calciumoxide and copper oxide, and the described noble metal component can be at least one of platinum, gold, rhodium, palladium and silver. The catalyst of the present invention consists of common metal oxide and a small amount of noble metal, can be efficiently applied to the catalytic oxidation of formaldehyde under the condition of room temperature. The catalyst of the present invention has the advantages of high catalytic activity and long duration, the conversion rate of formaldehyde can reach 100% under the condition of room temperature, and its products are carbon dioxide and water. The catalyst of the present invention, when in use without other additionally exterior conditions, saves energy, and has the value of popularization.