The invention relates to the field of environment protection, in particular to a method for treating ink wastewater. The method comprises the following steps: A, performing acid separation treatment, namely introducing ink wastewater into an acid separation tank, adjusting the pH value to 3-4, performing mechanical stirring for 15-30 minutes, leaving to stand for 30-45 minutes, and performing separation to obtain supernate A and precipitate A, and performing pressing filtration on the precipitate A to obtain pressing filtrate A; B, performing Fenton oxidation treatment, namely introducing the supernate A and the pressing filtrate A obtained in the step A into a Fenton oxidation tank, feeding Fe<2+> and H2O2, stirring, adjusting the pH value, performing separation to obtain supernate B and precipitate B, and performing pressing filtration on the precipitate B to obtain pressing filtrate B, wherein the ratio of Fe<2+> to H2O2 is (1:10)-(1:1), the stirring time is 10-20 minutes, and the pH value is adjusted to 6-8; C, performing MBR (membrane bio-reactor) reaction treatment, namely performing MBR microorganism degradation on the supernate B and the pressing filtrate B obtained in the step B, thereby obtaining purified water of which the COD (chemical oxygen demands) is less than 100, wherein the HRT (hydraulic retention time) of the MBR reaction treatment process is 4-6 hours. The technical scheme of the invention has the advantages of good organic matter treatment effect and stable effluent quality.