AbstractDifferent coagents including triallyl isocyanurate (TAIC) and trimethallyl isocyanurate (TMAIC) were applicated on peroxide curable fluoroelastomer (FKM). The cure efficiency for TAIC has found to be higher than TMAIC using rubber process analyzing (RPA). Moreover, TAIC also creates extra exothermal peak and greater enthalpy in Differential scanning calorimetry test. In addition, X‐ray photoelectron spectra further demonstrated that TMAIC expresses low tendency on crosslinking with cure sites and homopolymerization, the network formed by TMAIC expressed more prominent degradation under thermo‐oxidative aging which also supported by mechanical properties. In the end, different network modes were purposed corresponding to vulcanizates using TAIC and TMAIC, and the network consisting relatively long segments of TAIC polymer exhibits better stability during thermo‐oxidative aging.