The invention discloses a catalyst for preparing formaldehyde by methanol oxidation. According to the embodiment of the invention, the catalyst takes Mo(a)Ni(b)Fe(c)Bi(d)Pr(e)Co(f)Ce(g)V(h)Cr(i)A(j)O(k) as an active ingredient, wherein A is one or more of lithium, sodium, potassium and rubidium; a, b, c, d, e, f, g, h, i, j and k are atomic number of the elements; a is 10.0-20.0; b is 3.0-7.0; c is 1.0-4.0; d is 0-4.0, e is 0-3.0, f, g, h and i are 0-3.0; j is 0-0.5; k is the number of required oxygen atoms meeting valence of other elements. According to the catalyst disclosed by the invention, the yield of the target product and the stability of the catalyst are improved. On the other hand, the optimal reaction temperature can be lowered by the catalyst disclosed by the invention, and loss of molybdenum in the catalyst and by-products of over oxidation of carbon dioxide and the like are reduced.