An ultra-performance liquid chromatography coupled with time-of-flight mass spectrometric(UPLC-QTOF-MS) method was developed for the analysis of the differences among chemical compositions in Polygoni Multifori Radix processed by different methods.The samples were extracted with methanol by ultrasonic at room temperature and centrifuged.The extracts were analyzed by UPLC-QTOF-MS.After peak matching,peak alignment and noise filtering of characteristic peak extraction,the obtained data were analyzed by principal component analysis(PCA) and partial least-squares discriminant analysis(PLS-DA).The results demonstrated that there were significant differences among the samples of Polygoni Multifori Radix with different processing methods.Accurate mass measurements and CID experiments as well as the software of database searching and literature component identification were applied to identify.The chemical compositions of Polygoni Multifori Radix by different processing methods were analyzed,and 33 constituents were identified.Among them,15 constituents were the common chemical composition presented in different changing laws.The research provided experimental data for revealing the laws of different processing methods on metabolites of Polygoni Multifori Radix.