Abstract Reaction-formed SiC ceramic was fabricated by infiltrating molten Si into the carbon preform derived from a mixture of mesocarbon microbeads (MCMBs) and SiC powders which content was ranged from 10 to 40 wt.%. SiC powder limited the volume shrinkage of MCMBs during sintering and the porosity of the preform can be adjusted by altering SiC powder content. Aromatic layers in the carbon spheres derived from MCMBs were split below 1300 °C due to the graphitization effect of SiC powder. Molten Si infiltrated into the interfaces between carbon spheres as well as the microcracks inside the split spheres. As a result, network SiC ceramic was formed and some unreacted carbon distributed uniformly in the matrix. The reaction-formed SiC ceramics have excellent mechanical properties (the maximum bending strength, fracture toughness and hardness of 359 MPa, 4.4 MPa m 1/2 and 2348 Hv, respectively) and electrical conductivity (the lowest electric resistivity of 18.18 μΩ m).