In order to improve the ablation resistance of the thermal insulation layer in EPDM, maleic anhydride grafted EPDM (EPDM-gMAH) was used as the compatibilizer between the matrix and the inorganic filler. The mechanical properties and ablation resistance of the material were studied by means of tensile testing machine, multi-station-oxyacetylene ablation tester, thermogravimetric analyzer and scanning electron microscope. The test results show that: after adding EPDM-g-MAH, the line ablation rate and mass ablation rate of the thermal insulation layer material in EPDM are decreased, and with the increase of EPDM-g-MAH content, the formation of ablation rate is increased. The carbon layer is also getting denser and more uniform. On the other hand, when the mass fraction of EPDM-g-MAH is 9.5% and 14.3%, the mechanical properties of the EPDM inner thermal insulation layer material are greatly improved. Among them, when the mass fraction of EPDM-g-MAH is 14.3%, the comprehensive performance of the EPDM inner thermal insulation layer material is the best, the elongation at break is 7.8 times, which is increased by 1.191 times; the tensile strength is 6.7MPa, which is increased by 71.8%; The corrosion rate was 0.079 9mm·s-1, a decrease of 17.2%. This result will provide support for the application of more novel fillers in EPDM materials.