The inertia of silicon carbide (SiC) when creating polymer composite materials (PCM) often does not allow creating a high-quality final product. This is due to the weak interfacial interaction between the filler and the polymer. This paper presents a method for modifying silicon carbide with a controlled content of 3-aminopropyltriethoxysilane (APTES) on its surface. The modifier will create active functional groups on the surface of silicon carbide, and they will be the first to interact. In the study, a step-by-step assessment of the change in the surface of filler particles during the formation of reactive groups by IR spectroscopy was carried out and the effect of the proposed method on the bulk density of SiC particles was determined. The presented work contains data on the study of the adsorption kinetics of the filler after its modification, and describes the conditions under which the most complete addition of functional groups occurs during treatment with silane.The factors that can be used to vary the content of functional groups on the surface of silicon carbide, thus changing its activity, have been identified. The effectiveness of the proposed modification method is shown and samples with a reactive surface of SiC particles are obtained, which are the most promising for the creation of polymer composite materials.