The invention relates to a process for producing sodium sulfate using mirabilite decahydrate. The process comprises the steps that mirabilite decahydrate containing impurities is taken as a raw material and enters final effect evaporation equipment of a multi-effect evaporation system for peritectic evaporation at an evaporation temperature of 20-60 DEG C, the final effect evaporation equipment is provided with a jacket and a crystal growing tank, and is utilized to perform solid-liquid separation to obtain a sodium sulfate-containing solid and a final effect evaporation mother liquor, caustic soda and soda ash are added to the final effect evaporation mother liquor to be refined to obtain refined aqueous mirabilite and a precipitate, the refined aqueous mirabilite and the sodium sulfate-containing solid slurry in the final effect evaporation equipment reversely flow and are fed to first-effect evaporation equipment from last-but-one-effect evaporation equipment to be evaporated at an evaporation temperature of 60-150 DEG C and are subjected to solid-liquid separation to obtain a sodium sulfate product. The mirabilite decahydrate containing impurities is used as the raw material to be subjected to peritectic evaporation of mirabilite decahydrate, calcium, magnesium and zinc sulfate impurities are refined, and a sodium sulfate solution is evaporated to obtain the sodium sulfate product. The process has the characteristics of reduced refining amount of mirabilite, high-quality product, low cost, low energy consumption and the like.