MoSi2/R-SiC composite were obtained with different amount of MoSi2 in the SiC mixture powder and then sintered at 2 300 ℃. The XRD, SEM and impedance analyzer were used to study the microstructure, composition and volume resistivity. Experiment results showed that the 6H-SiC and Mo4.8Si3C0.6 with hexagonal structure were the main composition in materials obtained. The formation process was liquid MoSi2 losing Si and transforming into Mo-Si-C compounds and then reacting with SiC. The SiC grain was coated with Mo4.8Si3C0.6 compound. With the increase of additives, the thickness of the Mo4.8Si3C0.6 coating on SiC particles increased, and finally filled in the porosity in composite when the additive exceeded 10%. The density and porosity of the material increased at the same time. The mechanical properties changed little but the volume receptivity decreased significantly. Finally, the electronic conductive mechanism of the materials was discussed.