The invention discloses a preparation method of a polyepichlorohydrin-ethanediamine decolorizing agent. The preparation method comprises the following steps: (1), taking and placing
liquid paraffin in a four-port round bottom with a stirrer, a
thermometer and a
reflux condenser, and controlling the temperature to 0 DEG C-8 DEG C; (2), introducing
nitrogen gas in the
liquid paraffin, adding ethidene
diamine in a container, heating up while stirring, controlling the temperature to 20 DEG C-25 DEG C, and slowly dropwise adding polyepichlorohydrin to carry out
addition reaction; (3), continuously stirring for
thermal reaction after dropwise adding chloropropane, and cooling the temperature to 15 DEG C; (4), taking 33%
trimethylamine as a cross-linking agent to add into liquor, and reacting for 5 hours at 85 DEG C-90 DEG C; (5), cleaning a
solid product by methylbenzene, cleaning by
alcohol and water, vacuum-
drying at 60 DEG C and
grinding to obtain polyepichlorohydrin-ethanediamine. According to the preparation method, polyepichlorohydrin-ethanediamine is prepared by using polyepichlorohydrin and ethanediamine as materials and introducing a small amount of
trimethylamine cross-linking agent, and has the advantages of high molecular weight, good stability, good decolorizing effect and the like.