Random copolymers were prepared by cationic polymerization slurry method with isobutylene and p-methylstyrene as raw materials and AlEtCl₂/TMPCl as initiator.The free radical initiator AVBN was brominated under the shading condition of 55℃ to obtain brominated poly (isobutene-co-p-methylstyrene) random copolymer (BIMS) with fully saturated main chain structure.Tetramethylethylenediamine (TEMED) and potassium dicyclopentadienyl dicarboxylate [DCPD(COOK)₂],a self-made reversible vulcanizing agent,were used for vulcanization.The results showed that when the molar ratio of AlEtCl₂ to TMPCl was 18,the stability and repeatability of the reaction were good,and the molecular weight reached 24kg/mol.When the dosage of free radical initiator AVBN was 0.75×10^-3wt%,the effect of bromination reaction was better.Compared with TEMED,DCPD(COOK)₂ had better effect.The average tensile strength and elongation at break decrease by 10.6% and 16.5% during secondary vulcanization.When adding 5phr DCPD(COOK)₂,the tensile strength reached 4.9MPa,which had better reprocessability.