The effects of C3H8 on the microstructures of the films on Si (111) have been investigated by changing the concentration of C3H8 from 0.5% to 5%. 3C-SiC film on Si (111) grown at the C3H8 concentration of 1% with relatively high flow rate of SiH4 (30 sccm) is single crystal and free from the contamination of W2C. By comparing the deposition rates of the films on Si (111) and Si (100) at different concentrations of C3H8, SiC growth on Si (111) is much more dependent on C3H8 concentration than that on Si (100). From these results it is suggested that SiC growth on Si (111) is strongly influenced by hydrogen radicals generated from C3H8 decomposition by the plasma and forms single crystal easier than on Si(100). It is expected that 3C-SiC epitaxial growth on Si (111) has higher deposition rate and lower substrate temperature than on Si (100). The crystallinity has been investigated by a reflection electron diffraction (RED) and a X-ray diffraction (XRD). The thickness and the surface roughness of the films were investigated by an ellipsometric measurement.