Effects of crystal structure model combination, refinement range and scanning setting of X ray diffraction (XRD) on quantitative results of cement clinker were investigated by Rietveld method with Topas software. Results show that an important prerequisite for the accurate Rietveld quantitative phase analysis of clinker is to prepare the suitable and matched crystal structure model combination involved in the refinement. In order to guarantee the accuracy and precision in quantitative analysis, the minimum range of laboratory XRD data collection should be 2θ=(25°,70°). XRD scanning settings show that the effective counts of diffraction pattern has greater influence than resolution on quantitative refinement of clinker. With increase of scanning speed of continuous scanning type, the errors of Rietveld quantitative results of clinker become more obvious. For quantitative accuracy, the critical scanning speed of continuous scanning type should be 2(°)/min.