In this study, four kinds of coupling agents (CA), i.e., gamma-aminopropyltriethoxysilane (KH-550), (3-glycidyloxypropyl)trimethoxysilane (KH-560), isopropyl tri(di(2-ethylhexyl)pyrophosphate)titanate (NDZ-201), isopropyl tri(di(2-ethylhexyl)phosphate)titanate (NDZ-102), were used to investigate their influences on the thermal conductivity and morphology of aluminum (Al) particle reinforced epoxy composite. The results indicate that the thermal conductivity of the composites increases with increasing Al particles concentration up to 48 vol.%; the surface modification of Al particles has an appreciable effect on the thermal conductivity. The thermal conductivities of the composite containing 48 vol.% Al particles treated with the KH-550, KH-560, NDZ-201, and NDZ-102 couplers, are 1.29, 1.48, 1.27, and 1.36 W/m K, respectively, corresponding to 1.03 W/m K of that without surface treatment. Furthermore, the concentration of CA has an influence on the thermal conductivity of the composites.