Abstract: Xiong et al （2005）proposed the internal standard method for the clays. The original authors calculated the integral intensity of peaks by using the height. This method leads to the evident error presented in the internal standard quantitative analysis of attapulgite half peak width multiplied by peak curve. The contents in clay would be often higher than 100% when calculating with high purity attapulgite clay samples of palygorskite The peak areas are obtained by using software to integrating the intensity of peaks in current studies. The background in the text has been subtracted in all XRD patterns for discussion