This paper used a rubber processing analyzer (RPA) to study the effect of different amounts of epoxidized soybean oil and antioxidants on the rheological properties of brominated butyl rubber (BIIR) during the thermal oxidative aging process and discussed the cause of degradation and gel generation of BIIR.The results show that the rheological properties change trend is consistent with the GPC data,which proves that the thermal oxidative aging of BIIR is a process involving both molecular cross?linking and degradation;epoxidized soybean oil and antioxidants can greatly slow down the rate of the gel generation and molecular chain degradation during the aging process of BIIR.Different antioxidants have different anti?aging effects on BIIR.Antioxidant 1076 has a stronger inhibitory effect on oxidative degradation of BIIR than antioxidant 264.