The invention relates to a scheelite alkali decomposition slag treatment method which comprises the steps of (1) washing sodium: mixing a scheelite alkali decomposition slag and water, regulating pH of a solution to range from 6.5 to 7.5 through hydrochloric acid, and stirring to obtain a sodium chloride washing liquor and a filter residue; (2) dissolving low acid: stirring and mixing the filter residue in the step (1) and a hydrochloric acid solution with the initial H+ concentration ranging from 3.0mol/L to 5.0mol/L, reacting until the concentration of the H+ in the solution ranges from 0.1to 0.2mol/L, and obtaining a low-acid dissolution residue and a low-acid dissolution mother liquor; and (3) dissolving high acid: mixing the low-acid dissolution residue obtained in the step (2) and the hydrochloric acid solution with the initial H+ concentration ranging from 7.0mol/L to 8.0mol/L, adding H2O2, reacting until the concentration of the H+ in the solution ranges from 3.5 to 5.0mol/L,and obtaining a high-acid dissolution residue and a high-acid dissolution mother liquor. According to the method provided by the invention, ions such as sodium, iron and calcium in the scheelite alkali decomposition slag are leached, and meanwhile, valuable metals such as tungsten and tin are enriched.