The invention discloses a preparation method of alumina foam ceramic, and relates to the technical field of production of high-tech ceramic product foam ceramic. The preparation method comprises the steps of stirring polyether or polyester polyol with a catalyst, a surfactant and a foaming agent, adding nano magnesium oxide and alumina ceramic powder, uniformly stirring, adding a curing agent, completely and uniformly mixing, reacting and curing in a shaping container, implementing perforation treatment on a cured foam ceramic sponge, and sintering at high temperature to obtain the alumina foam ceramic. The preparation method disclosed by the invention, which directly forms a three-dimensional reticulated foam ceramic green body, can greatly reduce production process, guarantee uniform and consistent alumina foam ceramic structure prepared, greatly reduce manpower demand and manual labor, shorten production cycle, and can also improve stability of product performance.