Herb Epimedii, the Chinese name is Yinyanghuo, is one of the most well-known and frequently used Chinese herbal medicine with tonic, antirheumatic and aphrodisiac effects. As the major bioactive constituents of Epimedium plants, the flavonoids compounds showed androgenic, anti-oxidant, antidepressant, anti-osteoporosis, anti-apoptotic, stimulate angiogenesis, and anti-tumor activities. According to the relevant reports, various compounds have been identified in Epimedium species, and most of them were phenolic compounds including flavonoids and quinic acids. However, even though the standard crude drug Epimedium koreanum has a wildly application in quality control study, the quantity detection of icariin analogues of Epimedium koreanum is quietly rare. In this paper, qualitative and quantitative analysis of icariin analogues in Epimedium koreanum Nakai was performed by using ultra performance liquid chromatography and quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF MS) technology based on icariin fragmentation and its analogues fragment pathway. In the experiment, the active components in Herb Epimedium koreanum were extracted by accelerated solvent extraction system with 70% acetonitrile at 120℃ for 10 min, and the chromatographic separation was used Waters Acquity UPLC BEH-C18 (2.1 mm×150 mm, 1.7 μm), mobile phase was 0.05% formic acid and acetonitrile, then analyzed by Q-TOF-MS. Furthermore, by analyzing the mass spectrometric fragmentations of Icariin and Epimedin C, the fragmentation rules of this kind of compound were summed up. To our knowledge, Icariin and Epimedin C obtained from were 3-O-, 7-O- or 3, 7-di-O-glycosides, which frequently contained hexose, deoxyhexose, pentose. Therefore, based on the rules summarized the structures of unknown constituents of the icariin analogues in Epimedium koreanum could be detected. The results showed that Q-TOF MS provides abundant and stable information of fragment ions and 42 icariin analogues were identified, which were all eluted by 15%-70% acetonitrile. Among all these compounds, there are 4 compounds were firstly reported. This study is beneficial to discover icariin analogues in Epimediumand explore the leading compounds for drug development.