A new method is applied in this article to the quantitative phase analysis for weight factors of X-ray diffraction intensity. This method overcame the defect of traditional sampling and quantitative analysis method which only single out one plane web diffraction peaks for quantitative analysis from the phases of the sample to be tested. The method applied in this article is that the sample processing and taking measurements to the samples only once, then determining the weight factors by the intensity corresponding to n X-ray diffraction peaks from the phases of the sample to be tested. Thus we can get the relative percentage of each phase in the sample.