The invention relates to a method for producing metastannic acid and tin dioxide through a sulfuric acid method. The method comprises the steps that sulfuric acid and tin are put into a closed container in proportion, the liquid-solid mass ratio of the solution to tin is (5-14):1, and the initial acidity of a sulfuric acid solution is 10-200 g/l; subsequently, oxygen is introduced into the closedcontainer, pressurization and heating are conducted, and tin and sulfuric acid react to synthesize metastannic acid; the pressure of a closed reaction is larger than or equal to 0.5 MPa, the reactiontemperature is 90-200 DEG C, the reaction time is 2-8 h, after the reaction, liquid-solid separation is conducted, ammonium bicarbonate is added in the solid part, namely, a metastannic acid intermediate product for neutralization washing, after residual sulfuric acid is removed, centrifugal filtration and drying are conducted, and metastannic acid is obtained. Metastannic acid is calcined, and tin dioxide is obtained. According to the method, the production cost is low, three wastes are not generated in the technological process, and energy conservation and environmental friendliness are achieved. The prepared product is high in purity.