The invention discloses a synthetic method for free radical polymerization of advanced normality polyacrylonitrile. The synthetic method comprises the steps of adding an organic solvent and an initiator into a reactor, removing the air in the reactor and sealing the reactor, then putting the sealed reactor under magnetic field and constant temperature conditions, and adding an acrylonitrile monomer into the reactor to obtain the advanced normality polyacrylonitrile after polymerization reaction of free radicals. According to the synthetic method for free radical polymerization of the advanced normality polyacrylonitrile, the synthetic method is easy to operate, short in reaction time, high in PAN regularity and molecular weight, and high in monomer conversion rate.