Epitaxial 3C–SiC films have been deposited on Si(111) and Si(001) substrates via laser CVD with deposition rate of 12.32 and 15.56 μm/h, respectively. The activation energy of 3C–SiC on Si(111) and Si(001) was 80 and 160 kJ/mol, and the root mean square (RMS) roughness (w) as a function of the film thickness (h) follows power laws of w~h0.31 and w~h0.06, respectively. The growth mechanisms of epitaxial 3C–SiC films on Si(111) and Si(001) was investigated based on the structural analysis and roughness evolution.