Cationic polymerization method of isotactic polymer

The invention relates to a cationic polymerization method of an isotactic polymer. Polystyrene with crystallization property, which as high conversion rate, high molecular weight (weight average molecular weight Mw=1*105-3.5*105) and high isotacticity (the highest upper limit of the melting temperature can each 230 DEG C), and derivatives thereof can be obtained by carrying out styrene cation isotactic polymerization in a monomer solution comprising a monomer of styrene and the derivatives thereof and a solvent by adopting an initiation system comprising a cation source initiator, Lewis acid as well as a phenols, ethers, amine, amide or pyridine accessory ingredient. The isotacticity of polymerization products can be adjusted in a certain range, and meanwhile, the favorable crystallization property of the polymerization product can endow materials with higher use temperature and good physical and mechanical properties.