The invention provides a double-layer centrifugal fan. The double-layer centrifugal fan comprises a housing and fan blades, wherein the fan blades comprise large-diameter fan blades and small-diameterfan blades; a first fixed table, a large fan blade framework and a first fixed shaft hole are arranged on the large-diameter fan blades; a second fixed table, a small fan blade framework and a secondfixed shaft hole are arranged on the small-diameter fan blades; a central shaft is arranged inside the housing; the large-diameter fan blades and the small-diameter fan blades are blocked together upand down through the central shaft; the central shaft penetrates through the first fixed shaft hole and the second fixed shaft hole; and the large-diameter fan blades and the small-diameter fan blades fix the central shaft through the first fixed table and the second fixed table. According to the double-layer centrifugal fan provided by the invention, the large-diameter fan blades and the small-diameter fan blades are arranged on the mounting frame, and the two fan blades are matched to solve a ventilating and heat-dissipating problem inside an electrical appliance assembly. One motor drive assembly drives rotary operation of the central shaft to solve the cooling problem of electrical appliance elements in two adjacent small spaces; and meanwhile, power loss is saved.