Abstract: ANSYS was used to simulate the thermal conduction process of TiB₂/Cu composites with different TiB₂ particle sizes. The TiB₂/Cu composites with different TiB₂ particle sizes were prepared by powder metallurgy. LINSEIS LFA1600 laser thermal conductivity instrument was used to determine the thermal conductivity of the TiB₂/Cu composites ranging from room temperature to 280℃, and the measured values were compared with the simulation results. The simulation results are in good agreement with the measured values. In the range of 50-200℃, the thermal conductivities of the TiB₂/Cu composites fluctuate in the range of 6%-9%. When the temperature is above 200℃, both the simulated results and the measured values increase with the increase of temperature, and they match well with each other. This is because the large difference of their thermal expansion coefficients in the interface between TiB₂ and Cu below 200℃ is not considered in the simulation process. When the temperature is above 200℃, the simulation results have good accordance with the measured values. At 200℃, due to the influence of two-phase thermal expansion coefficients, the equivalent stress at the internal interface of the composite is larger than the yield strength of the Cu matrix, thus causing plastic deformation, which leads to a significant change in the thermal conductivity. In addition, the thermal conductivity increases and then decreases with the increase of particle size, and reaches its maximum value at 10 μm. This is because when the particle diameter is less than the critical average diameter, the increased particle diameter reduces the number of interfaces, thus reducing the interfacial thermal resistance. When the particle diameter is larger than the critical mean diameter, the mean free path l greatly increases and the thermal conductivity reduces.