A novel sulfonated polytriazine (SP) is synthesized by the condensation polymerization reaction of 2-(4,6-dichloro-1,3,5-triazin-2-ylamino)benzene-1,4-disulfonic acid (Compound I) and 1,4-diaminobenzene. The structure of SP is characterized by FTIR spectroscopy, 1H-NMR, and gel permeation chromatography (GPC). The flocculation performances for the cationic dyes are evaluated. The experimental results show that SP can efficiently remove the color of wastewater containing cationic dyes. The rates of color removal from C.I. Basic red 18 and C.I. Basic blue 9 reach as high as 99.6% and 98.5%, respectively. The synthesized SP shows high adsorption capacities of 1719 and 1988 mg/g for C.I. Basic blue 9 and C.I. Basic red 18, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39669.