The invention relates to the technical field of brine treatment, in particular to a method for removing iron ions from sodium sulfate type brine. The method comprises the following steps: (1) preparation of a pre-oxidation assistant: a specific amount of potassium permanganate is added in a refined brine liquid which consists of chemical components comprising less than or equal to 10mg/L of Ca<2+>, less than or equal to 5mg/L of Mg<2+> and 300+/-5 g/L of NaCl; (2) the pre-oxidation assistant is added into original brine to ensure that the content of potassium permanganate in the original brine is 0.1-5 mg/L; (3) addition of sodium carbonate and caustic soda to adjust pH: sodium carbonate and caustic soda are added to original brine mixture liquid obtained in step (2), sodium carbonate is added to remove calcium ions, caustic soda is added to adjust pH value to be 10-11.5, and reaction continues for 1.5 h; (4) addition of a flocculation precipitant. The chemical assistant prepared in the process of using the method provided by the invention leads to no secondary pollution; the pre-oxidation assistant can be applied to primary brine manufacture process in the way of the continuous method, and the method of preparing and adding the pre-oxidation assistant is simple and has no negative impact on original manufacture process and product quality; compared with ordinary natural oxidation method which takes about 20 h, pre-oxidation takes 1-5 min, so that time is saved, and higher efficiency is achieved.