The invention provides a method for producing aluminum oxide from a raw meal nodule. The method comprises the following steps: conducting reaction on a high-aluminum fly ash and a sodium hydroxide solution to pre-desilicate to obtain a fly ash filter cake and a desilicating solution; adding the desilicated fly ash filter cake into the sodium hydroxide solution to form a mixed size, adding powders like limestone, calcined lime and anthracite under the stirring condition, stirring and solidifying, pelletizing with a pelletizing machine to obtain the raw meal nodule drying the raw meal nodule outside a kiln, then calcinating to form a clinker in the rotary kiln, mixing the clinker and a correction liquor to dissolve, implementing solid-liquid separation after dissolving to acquire a dissolved slag and a rough sodium aluminate solution, implementing one-stage desilication and two-stage desilication on the acquired rough sodium aluminate solution, and implementing carbonating disintergration on an obtained fine sodium aluminate solution to obtain an aluminum hydroxide product. The method provided by the invention greatly reduces the energy consumed in the sintering of a raw meal, the yield is increased, the equipment cost and the operation difficulty are reduced, and a high-purity aluminum oxide product is also acquired.