Abstract: Star polyacrylamide(SPAM) was synthesized by the aqueous solution copolymerization method. The effect of various initiator weight dosage，molecular weight regulation agent dosage and temperature of copolymerization system on SPAM intrinsic viscosity waas analyzed and discussed with the orthogonal experiment method.The optimum conditions of reaction were obtained as follows: monomer mass concentration 15%，temperature of copolymerization 35℃，initiator weight dosage 0.04% (relative to monomer mass)，chelate agent dosage 0.005%，anticrosslinking agent dosage 0.015%，pH value of copolymerzation system 5 and SPAM intrinsic viscosity 989.2 mL•g－1. Chloramination of SPAM was conducted at 35 and then was added into starch solution. After reaction for 40 minutes at 40～50℃ the SPAM grafted starch flocculuating agent was obtained.The application experiment showedthat the SPAM grafted starch flocculating agent has good solubility，