Adding non-carboxylic peroxide, dicumyl peroxide (DCP), to vulcanize alumina and natural rubber composite materials can increase the tensile stress, elongation at break, ductility, modulus, and crosslink density. Dicumyl peroxide acts as a catalyst and vulcanizing agent to crosslink elastomer molecules. Vulcanization time and temperature of elastomer added 60 phr Al2O3 are 170๐C for 8 min lower than the thalf-life of DCP which is 178๐C for 1 min. The tensile elastic modulus values are 0.6183, 0.6500, and 3.500 MPa for 1, 3, and 5 phr of DCP, respectively. The elongation at break of 1, 3, and 5 phr of DCP were 633.26, 182.88, and 65.86, respectively. The crosslink density values are equal to 2.7029x10-4, 2.25x10-4, and 6.29x10-4 mol/cm3 respectively. Furthermore, the received results correspond to the results investigated by Simultaneous Thermal Analysis (STA), Scanning Electron Microscope (SEM), and chemical functional groups by FTIR.