Abstract: Bromamine acid (1-amino-4-bromo-anthraquinone-2-sulfonic acid sodium) aqueous solution was selected as the sample in this study. Separation of organic matter in bromamine acid aqueous solution by natural cold energy in winter，and the change of organic matter in freezing field were investigated. The results indicated that the ice sample can be obviously divided into four layers as slightly polluted layer，clean layer，mixed layer and precipitated layer after bromamine acid aqueous solution was completely frozen. With the increase of initial concentration，the organic removal rate decreased in the slightly polluted layer. In the clean layer，with the initial concentration from 50mg/L to 4000mg/L，its volume decreased from 76.5％ to 35.3％ of the total sample volume，and its total organic carbon (TOC) kept at 6 mg/L，not affected by the initial concentration less than 2000mg/L. The slightly polluted layer can be eliminated by introducing seed ice at the solution critical temperature，and the optimal pre-cooling temperature was 1℃. There was no significant impact on freezing separation when introducing seed ice at difference initial concentrations. In the same freezing conditions，ice layer was separated，and residual solution was frozen again repeatedly. In this process，bromamine acid was separated in the form of solid granules. With repeated separation and freezing，the organic matter removal rate decreased in the ice sample separated.