Abstract: Removal of organic matter and carbonate is one of the important steps in the pretreatment of X-ray diffraction (XRD) measurement of clay minerals, and the different reagent concentrations, reagent types and reaction conditions may lead to different experimental results. To improve the accuracy of clay mineral analysis data, it is important to clarify the influence of various processing methods on clay minerals. In this study, we conducted comparative a series of experiments on four standard clay mineral samples (montmorillonite, chlorite, kaolinite, and illite) treated with different types and concentrations of acids and hydrogen peroxide under different reaction conditions, and evaluated the effects of various treatments on different clay minerals by XRD analysis. The results showed that hydrogen peroxide treatment at concentrations of 10% and 30% did not affect any of the four clay minerals; hydrochloric acid treatment would destroy the crystal structure of montmorillonite to different degrees, and the destruction of the crystal structure of montmorillonite gradually increased with the concentration of hydrochloric acid from 0.1, 0.5 to 1 mol/L. Therefore, we suggested that when using hydrochloric acid to remove carbonate, the concentration should not exceed 0.5 mol/L. The treatment with acetic acid at a concentration of 10% does not damage the crystal structure of any of the four clay minerals, and yet the intensity of the diffraction peaks may be significantly increased by the adhesion of organic acid molecules to the mineral crystal surfaces, especially for montmorillonite, which may lead to a high calculation of the relative content of montmorillonite in practical applications.tive content of montmorillonite in practical applications.