Abstract: Thermal conductivity of SiC_p/Al composites was simulated by finite element method. The multi-particle random distribution models of composite in plane were established. moreorer, the effect of SiC_particle volume fraction on thermal conductivity of SiC_p/Al composites was also investigated. The composites with 38. 4%~63. 5% volume fraction of SiC_particle were prepared by pressureless infiltration through preform and dual diameter of particle,the thermal conductivity of composites was measured and compared with the simulated values. The result show that the thermal conductivity of the composites decreases with increasing of SiC volume fraction, and declined at a slower pace when SiC volume fraction reaches about 50%; With the proportion of coarse particles increased,The thermal conductivity of dual diameter particle composite material was also increased; The measured values of the thermal conductivity of the composites matched the simulated values well,the thermal conductivity of composites by preform was about 10% lower than the simulated values,the thermal conductivity of composites by dual diameter of particle was about 2% lower than the simulated values.