This study aims to investigate the difference in the chemical composition of Atractylodis Macrocephalae Rhizoma(AMR) before and after processing with rice-washed water(AMR-RW).In this study,the HPLC method was used to compare the fingerprints of AMR before and after processing with rice-washed water,and the content changes of atracylenolide Ⅰ,atracylenolide Ⅱ,atractylenolide Ⅲ,and atractylon were measured at the same time.Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used for the stoichiometry study to screen the differential components of AMR before and after processing with rice-washed water.The results showed that after processing with rice-washed water,the common peaks of the fingerprint changed from 11 to 9,the contents of four components changed significantly,and there might be a transformation between components.The content of atracylenolide Ⅰ,atracylenolide Ⅱ,and atractylon increased after processing with rice-washed water.In contrast,the content of atractylenolide Ⅲ decreased after processing with rice-washed water.This might be related to the instability of atractylenolide Ⅲ under heat,which would partially transform into atracylenolide Ⅱ.The results of the chemometric analysis showed that AMR and AMR-RW could be distinguished obviously.Atractylenolide Ⅲ and atracylenolide Ⅱ are the main markers of the difference in content before and after processing with rice-washed water.This study provides a scientific basis for the quality standard research of AMR-RW.