The work aims to use hydrogen peroxide (H2O2) solution and vinyltrimethoxysilane (A171) to activate and graft small molecules onto flaky magnetic metal absorbent particles, and compound the modified absorbing agent with organic silicone resin to obtain chemical bonding at the absorbent matrix interface, and to develop a temperature resistant absorbing coating with high filling, high adhesion, and high magnetic permeability. By changing the temperature and reaction time, the optimal conditions for activating absorbents with H2O2 solution were explored. A chemical bond connection between the absorbent and the matrix was formed in a silicon hydrogen addition reaction between the ethylene group of A171 and organic silicone resin. The results showed that the untreated and H2O2 activated absorbent particles were modified with 3% and 7% A171 grafting to obtain the best wettability, indicating that surface activation could effectively enhance the grafting effect; As the grafting amount of A171 increased, the density of the coating increased, the adhesion was improved, and the magnetic permeability increased; When the grafting amount of A171 was 7%, the coating density increased from (2.05±0.04) g/cm3 to (2.27±0.03) g/cm3, the adhesion increased by 52.6% from its original value of (5.63±0.11) MPa to (8.59±0.13) MPa; The peak reflectivity of the 1 mm coating increased from −5.01 dB to −6.12 dB. After 20 hours of heat treatment at 300 ℃, the reflectivity of the 1 mm coating still remained at −5.98 dB, maintaining good temperature resistance. In conclusion, the activation treatment of flaky absorbents with H2O2 solution can increase the grafting content of A171 on the surface of the absorbent, significantly improve the filling ability of the absorbent on the organic silicone resin matrix, and improve the adhesion, magnetic permeability, and absorption performance of the temperature resistant absorbing coating.