Polyamine flocculants were synthesized by the polycondensation of dimethylamine and epichlorohydrin, in which organic amines, e.g. 1,2-diaminoethane, were used as modifying agents. Different products were obtained by varying the reaction parameters, such as the molar ratio ofepichlorohydrin to dimethylamine, the amount of 1,2-diaminoethane and reaction temperature. The polyamine flocculants were characterized bytransmission electron microscope (TEM). Their flocculation performance was evaluated with simulated dye liquor and actual printing and dyeingwastewater. The behavior of the flocculantswas compared with that of inorganic coagulant, polyaluminum chloride (PAC). The experimental resultsshow that polyamine with the highest viscosity and cationicity could be prepared under following conditions: an epichlorohydrin to dimethylaminemolar ratio of 1.5, a reaction temperature of 70 ◦C, a 3% content of 1,2-diaminoethane in the total reaction monomers and a reaction time of 7 h.Polyamine polymers can, as flocculants for treating simulated and actual dye wastewater, remove color and COD efficiently. The rate of colorremoval from reactive red liquor, reactive blue liquor and reductive yellow liquor reached as high as 96%, 97% and 96%, respectively. The highestefficiency of color removal and COD removal from polyamine for treating dye wastewater was 90% and 89%, respectively.