Crystalline 3C-SiC films were grown on Si substrate whose surface has been modified with SiNx by NH3 nitridation and their qualities were examined. The growth rate of 3C-SiC film increased with tile increase of tetramethysilane (TMS) partial pressure, The growth reaction of 3C-SiC film was the Ist order with respect to TMS partial pressure. When SiC films were grown on pure Si surface, voids were observed in the silicon side of the SiC/Si interface, But void-free SIC films with a flat and smooth film/ substrate interface were grown on 60-min nitrided Si surfaces. Crystal quality of 3C-SiC grown on tile nitrided Si substrate was better than that on pure Si. The growth mechanism of 3C-SiC films on the nitrided Si substrate was discussed in detail in this work.