It is very difficult to obtain SiC polytypes distribution by normal X-ray powder diffraction quantitative phase analysis methods. The whole pattern fitting Rietveld method is introduced to address this problem. The principle and advantages of Rietveld method in determining SiC polytypes distribution are described. The final results show that the distribution of the most common four SiC polytypes, 6H, 4H, 3C and 15R, can be given accurately. The detection limits of each polytypes are also estimated based on their standard deviations