To research the difference of chemical constituents in Lysimachiae Herba and its relative byproducts (Dichondrae Herba and Glechomae Herba) based on LC-MS,and provide reference for the rational use of Lysimachiae Herba and its relative byproducts.The difference of chemical constituents in Lysimachiae Herba and its relative byproducts was analyzed by using ultra-fast liquid chromatography coupled with triple quadrupole-time of flight tandem mass spectrometry (UFLC-Triple TOF-MS/MS) coupled with multivariate statistical analysis.Besides,a method based on ultra-fast liquid chromatography-triple quadrupole-linear ion trap mass spectrometry (UFLC-QTRAP-MS/MS) was developed for the simultaneous determination of common differential constituents in Lysimachiae Herba and its relative byproducts.Finally,a total of 13 constituents were identified and inferred,and six common differential constituents were screened out,which were chlorogenic acid,hyperin,rutin,isoquercitrin,quercetin,and kaempferol 3-O-rutinoside.In order to preliminarily explore the possible reasons for the differences in the efficacy of Lysimachiae Herba and its relative byproducts,the content of six common differential constituents was determined simultaneously.The results showed that the linear correlation coefficients (r) of six constituents were greater than 0.999 4 and the method featured a good precision,repeatability,and stability;The average recoveries were between 99.77% and 101.89%,with RSD less than 2.19%.The results showed that the content of rutin and kaempferol 3-O-rutinoside was higher in Lysimachiae Herba,and the other four constituents was higher in Dichondrae Herba,while the content of all six components was lower in Glechomae Herba.The method established in this study is accurate and reliable,and can provide basic information for the establishment of a comprehensive quality evaluation system for Lysimachiae Herba.