Polyacrylic acid dispersant was prepared by free radical polymerization with acrylic acid as monomer, hydrogen peroxide as initiator and isopropanol as chain transfer agent. The molecular weight and structure were characterized by gel chromatography and fourier infrared spectroscopy. The impurity elements of the synthetic polyacrylic acid dispersant were analyzed by ion chromatography and inductively coupled plasma spectroscopy. The thermal stability was evaluated under the operating conditions of nuclear power plants. Finally, the synthetic polyacrylic acid dispersant was added to the second circuit of a domestic nuclear power plant. The characterization results showed that the average weight of the synthesized polyacrylic acid dispersant was 61,586, the content of impurity elements was less than 3 mg/kg. The thermal decomposition half-life of the synthesized polyacrylic acid dispersant was more than 1 h at 280 ℃. After the injection of polyacrylic acid into the secondary side of the steam generator of the nuclear power plant, the steam generator blowdown iron removal efficiency increased from 2% to 51,393%, and the dry weight of corrosion products discharged through the blowdown filter was 66 kg. The results of engineering application of polyacrylic acid dispersant show that the online addition of polyacrylic acid dispersant to the secondary circuit of nuclear power plant can efficiently disperse the corrosion products in the secondary side of the steam generator and improve the blowdown iron removal efficiency.