Abstract: Multi-band compatible composite coating materials are in urgent demand in the field of civil-military integration and are a current research hotspot. Coating binder is an important component affecting the mechanical, infrared and dielectric properties of coatings. However, most organic binders have high infrared emissivity, and the low emissivity fillers often fail to harmonize the contradiction between mechanical properties, infrared stealth and radar transmittance properties. A composite coating with low infrared emissivity and low dielectric loss characteristics was prepared by modifying ethylene propylene diene (EPDM) binder with acrylic acid (AA) and maleic anhydride (MAH) as grafting monomers, and using EPDM rubber as binder before and after modification, floating aluminum powder and short-cut antistatic carbon fiber as fillers. The influence laws of modified monomer type and dosage on the binder itself and on the performance of the composite coating with added filler were systematically investigated. The results show that the infrared emissivity of the composite coatings slightly increases with the increase of the content of grafted monomers, while the radar transmittance properties remain basically unchanged. The graft modification of the binder improves the compatibility, wettability and interfacial bonding between the filler and binder, which significantly improves the mechanical and comprehensive properties of the composite coating. The tensile strength (σ_b) and elongation at break (e) of the composite coating can be increased by 32% and 18%, respectively, by appropriate graft modification. The mechanism of the effect of AA and MAH graft modification on the coating properties was revealed from the aspects of polarity, branching and cross-linking.