The reaction activation energy of self- polymerization of zinc dimethacrylate (ZDMA), vulcanization of hydrogenated nitrile rubber (HNBR) and corresponding reaction ingredient in ZDMA reinforced HNBR with 2, 4-di-tert-butylisopropylbenzene peroxide (BIBP) was determined by DSC. The results show that in single system, the reaction activation energy of HNBR’s vulcanization is higher than that of ZDMA’s self-polymerization. While in the ZDMA reinforced HNBR system, the reaction activation energy of ZDMA’s self-polymerization is higher than that of HNBR’s vulcanization and crosslinking between HNBR and polymerized ZDMA (PZDMA) due to the co-crosslinking function of ZDMA. The change of activation energy indicates that in the ZDMA reinforced HNBR system, higher cure temperature is beneficial to the self-polymerization of ZDMA, while less crosslinks tend to be formed in HNBR and between HNBR and PZDMA. The results also show that with the increasing of cure temperature, HNBR vulcanizates have lower hardness and modulus due to the decrease of crosslink density, and higher tensile and tear strength resulted from the formation of more reinforcing particles of PZDMA. The result is coincided with the obtained reaction activation energy.