Preparation method and application of halogenated copolymer, system for preparing halogenated copolymer and application

The invention relates to the field of halogenated copolymers, and discloses a preparation method and application of a halogenated copolymer, and a system for preparing the halogenated copolymer and application. The preparation method comprises the following steps: S1, carrying out halogenation reaction on a copolymer solution, a halogenation reagent and a halogenation initiator to obtain a halogenated copolymer solution; s2, in the presence of an alkaline substance, carrying out a neutralization reaction on the halogenated copolymer solution to obtain a halogenated copolymer; wherein the halogenation reaction is an N-stage halogenation reaction, nitrogen is introduced in the Nth-stage halogenation reaction, and N is greater than or equal to 2. According to the preparation method, nitrogen is introduced in the halogenation reaction stage, so that side reactions can be inhibited, the gel content of the product is reduced, meanwhile, most of by-product hydrogen halide can be carried away, and the use amount of a