Cationic poly(amide-ester) (PAE-GTAC) was synthesized from dendritic poly(amine-ester)[PAE(NH2)8] and glycidyl trimethyl ammonium chloride(GTAC). The effects of reaction temperature, reaction time and the mole ratio of reactants on the product yield were studied through orthogonal experiments. The PAE-GTAC structure was identified by means of FTIR and NMR. The effects of the amount of PAE-GTAC , centrifugation time and pH on the removal of Cr3 and dyes(methyl orange、titan yellow and xylenol orange )were discussed. Under the optimum conditions: reaction temperature 45 ℃，reaction time 5 h and n(PAE(NH2)8)∶n(GTAC)= 1:16，isopropanol as solvent, the yield of PAE-GTAC was 66.28%. At 25℃, pH=8.87, a rotational speed of 3000 r/min for centrifugation 13min with 25mL PAE-GTAC (c=0.01 mol/L) was treated 10mL CrCl3 (c=0.1mol/L) solution, the highest removal rate was 97.56%; at 25℃, pH=1.51、2.03 and 1.52, after oscillated 15min, a rotational speed of 3000 r/min for centrifugation 10min with 25mL PAE-GTAC (c=0.01 mol/L) was treated 10mL dyes (c=1.2?0-5 mol/L) solution, the highest removal rate of methyl orange, titan yellow and xylenol orange was 84.16%、92.25% and 97.35% respectively.