The reactive enhanced filler zinc methacrylate (ZDMA) can endow EPDM with characteristics of high hardness, high elasticity, low internal friction, high strength and high elongation at break. However, the specific compositions of EPDM/ZDMA and the structural changes of crosslinked network under the action of tensile, compression forces or high temperature are still not clear. Therefore, in this paper, differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) were used to confirm that the total crosslinked network of EPDM/ZDMA composite is mainly composed of ionic crosslinked network and covalent crosslinked network. The changes of covalent bond crosslinking density (vr1) and ionic bond crosslinking density (vr2) in EPDM/ZDMA composite under tensile, compression force and aging at different temperatures were studied through the combination of swelling equilibrium and acid extraction method. The results indicate that both vr1 and vr2 decrease in different degrees under tensile stress. When ZDMA content is low, vr1 decreases greatly, while vr2 decreases more when ZDMA content is higher. At the initial stage of compression stress, both vr1 and vr2 decrease greatly, but with the extension of compression time, the ionic crosslinked network continues to be destroyed, while the covalent crosslinked network is maintained. The ionic bond crosslinking network of EPDM/ZDMA composite system has a sensitive temperature between 90 ℃ and 120 ℃. When the temperature is lower than 90 ℃, the ionic bond crosslinking density has almost no effect after 24 h aging. However, when the temperature is higher than 120 ℃, the ionic bond crosslinking density decreases rapidly after 24 h aging.