A method for recovering sodium hydroxide in an H acid alkali fusion reaction material is provided; the method comprises the following steps: at room temperature, adding a solvent azeotropic with water into the alkali fusion material, stirring, and carrying out heating reflux, water carrying and water diversion; after water carrying is finished, cooling to room temperature, adding an alcohol solvent, carrying out heating stirring, carrying out cooling suction filtration, and stratifying a mother liquid, to obtain an alcohol solution containing sodium hydroxide; and distilling to remove the solvent alcohol under reduced pressure, and reusing for an alkali fusion reaction. The filter cake obtained from suction filtration is subjected to normal acidification to obtain an H acid product. The process flow is simple, the conditions are mild, and the recovery rate of the alkali is more than 95%. By the method, the sodium hydroxide consumption of the alkali fusion reaction is reduced to about 0.25 time of the original consumption, the consumption of acidified sulfuric acid is reduced to about 0.25 time of the original consumption, more importantly, the high-salt-content wastewater quantity and wastewater treatment costs are reduced, and the environmental pollution is reduced.