The unsaturated linear (UL) copolymer of methyl acrylate (MA), 1-octene, and allyl glycidyl ether (AGE) and the long-chain branch (LCB) copolymer of MA, 1-octene, and 1,7-octadiene were synthesized, respectively, via AlCl3-catalyzed radical copolymerization, and then both UL and LCB copolymers were vulcanized using dicumyl peroxide (DCP) curing system. For UL copolymer, cross-linking heat first increases with DCP dosages and then decreases when DCP dosages increases further to 2.5, that is quite reasonable to relate with cross-link and degradation reactions during vulcanization. However, the reaction heat flow curves of DCP-LCB curing system with DCP dosages ranging from 1.5 phr to 3.5 phr exhibit a bimodal-like "crosslinking" endotherm, suggesting a two-stage reaction of intramolecular cross-linking and intermolecular cross-linking. Results from dynamic mechanical analysis and tensile tests confirm that LCB copolymers are propitious to form effective networks at low DCP dosages and to keep the vulcanized topological structure with redundant DCP.