The invention relates to a method for producing wollastonite and aluminum oxide according to a coal ash sintering hydrothermal method. The method provided by the invention comprises the following steps: mixing coal ash with a chemical beneficiation solvent for chemical beneficiation so as to prepare concentrate of coal ash; (2) preparing raw slurry with the concentrate of coal ash; (3) sintering to prepare a clinker; (4) dissolving out the clinker and separating and washing the clinker to obtain a dicalcium silicate washing material; (5) preparing xonotlite precursor original slurry; (6) hydrothermally synthesizing to prepare an xonotlite precursor; (7) hydrothermally synthesizing to prepare xonotlite slurry; (8) calcining to prepare the wollastonite. The method provided by the invention can be used for effectively solving the problems and overcoming the defects that in the prior art, the consumption of limestone is great, the consumption of energy resources is great, and the quantity of slag is great. Coal ash is comprehensively utilized to produce wollastonite and aluminum oxide, so that the silicon mineral source is replaced, the bauxite resource is replaced, and resources such as land are also saved; moreover, large-scaled economic production can be realized.