The invention provides a catalyst, which comprises a carrier and a composite metal oxide MoaBibXcYdZeOf, wherein X is at least one selected from Fe, Co and Ni, Y is at least one selected from Na, K, Cs, Ba, La and Ce, Z is at least one selected from V, W and Cr, a ratio of a to b to c to d to e is 12:(0.5-2.5):(0.5-3):(0.005-0.5):(0.5-10), and f is the total number of oxygen atoms required for meeting the valence of other elements. According to the present invention, with the application of the catalyst in preparation of acrylic acid and acrolein through selective oxidation of propylene, the catalyst has high specific selectivity and excellent carbon deposition resistance, the conversion rate of propylene is relatively high, the yield of the target product is high, the target of directional and selective production of acrylic acid or acrolein is achieved, and the service life of the catalyst is greatly prolonged.