The objective of this study is to propose an optimum operating conditions in the treatment of plate wastewater by Fenton`s oxidation and membrane separation process. Optimum operating conditions for Fenton`s oxidation were pH 4, a reaction time of 30 min and the dosage of H₂O₂ and FeSO₄·7H₂O was 550 ㎎ /L and 500 ㎎ /L, respectively. Membrane separation was conducted as post-treatment using supernatant after pre-treatment by Fenton`s oxidation. COD could be reduced from 70.89 ㎎ /L(RO feed) to 14.44 ㎎ /L(79.63% removal). CN and Zn²+ were removed from 1.45 ㎎ /L and 48.00 ㎎ /L in the RO feed to 0.16 ㎎ /L and 1.60 ㎎ /L in the treated water, respectively. Excellent CN (88.97%) and Zn²+(96.67%) removals by RO were obtained.