Abstract: Clay mineral is one of the most important components of soil and rock, and its quantification of geological samples is of great significance to the study of mineralogical characteristics and geological evolution.X-ray diffraction (XRD) analysis is the most widely used method for the quantitative analysis of clay minerals.Modified Schultz method and reference intensity ratio (RIR) method are traditionally widely selected for quantification of clay minerals.However, quantification accuracy of the two methods is low.Recently, a new quantitative analysis method of clay mineral, mineral intensity factor (MIF) method, is confirmed to be more accurate.This method quantifies clay mineral using the specific MIF value which is believed to the unique value for each kind of clay mineral.However, several MIF factors of clay minerals such as montmorillonite and illite have not been given in the previous reports until now.In this paper, the accuracy of the MIF method was evaluated by quantifying artificially mixed samples composed by different pure clay minerals.Moreover, MIF factors of montmorillonite and illite were obtained.The MIF factors of montmorillonite and illite are 0.093 and 0.084, respectively.