Cationic polymerization initiation system and application thereof

The invention relates to a cationic polymerization initiation system and an application to the preparation of polyisobutene and butyl rubber. The initiation system based on Lewis acid adopts water, HCl or a tert-chlorine compound RCl as an initiator and induces a fluorine-contained aromatic compound or simultaneously induces the fluorine-contained aromatic compound and an organic compound containing oxygen, sulfur and nitrogen atoms so as to uniformly disperse polymerization reaction products in a reaction system, effectively improve the mass transfer and the heat transfer of a polymerization reaction system, adjust the molecular weight and the molecular weight distribution of an obtained polymer in a certain range and achieve the aim of improving the molecular weight of the polymer product and improving the molecular weight distribution under the condition of suitably improving a polymerization temperature (such as about 60 DEG C below zero).