Using a mixture of water and ethanol as medium, acrylamide (AM) as monomer, polymethylacrylic acid trithiocarbonates (PMAA-TTC) as chain transfer agent and AIBA as initiator, the polyacrylamide (PAM) was synthesized by dispersion polymerization. The effect of reaction media, monomer, initiator, reaction temperature and solid content on polymerization were investigated. The optimum reaction conditions were that the mass ratio of ethanol and water was 7∶3, the molar ratio of AM/Macro-CTA/AIBA was 6 000∶5∶1, the temperature was 50 ℃and the solid content was 10%.