The thermal conductivity of Cu/Kovar composites was improved by suppressing element diffusion at the interfaces through the formation of FeWO₄ coating on the Kovar particles via vacuum deposition. Cu matrix composites reinforced with unmodified (Cu/Kovar) and modified Kovar (Cu/Kovar@) particles were prepared by hot pressing. The results demonstrate that the interfaces of Cu/FeWO₄ and FeWO₄/Kovar in the Cu/Kovar@ composites exhibit strong bonding, and no secondary phase is generated. The presence of FeWO₄ impedes interfacial diffusion within the composite, resulting in an increase in grain size and a decrease in dislocation density. After surface modification of the Kovar particle, the thermal conductivity of Cu/Kovar@ composite is increased by 110% from 40.6 to 85.6 W·m^-1·K^-1. Moreover, the thermal expansion coefficient of the Cu/Kovar@ composite is 9.8×10^-6 K^-1, meeting the electronic packaging requirements.