Abstract: Epimedium has been widely used for invigorating sex, as well as rheumatism, strengthening muscles and bones. Recent report has shown that some flavonoids impart significant effects in the treatment of breast cancer, liver cancer, and leukemia. The recognition of the health benefits of Epimedium has resulted in extensive use of wild resources, and artificial cultivation is the only way to achieve sustainable use of resources. Epimedium pseudowushannense B.L.Guo is intended to achieve the first cultivated species，but Epimedium sagittatum (Sieb. et Zucc.) Maxim technology is not yet mature. In order to take further study of the two kinds of Epimedium, and provide the theoretical basis for the actual production.The diurnal variation of photosynthetic and eco-physiological characteristics of these two species was studied by the CI-340 Portable Photosynthesis System under natural conditions. The net photosynthetic rate (Pn)，stomatal conductance (C)，intercellular CO2 concentration (Ci)，photosynthetically active radiation (PAR)，relative humidity (RH)，air temperature (Ta)，apparent mesophyll conductance (ALMC)，transpiration rate (E)，leaf temperature (Tl)，water use efficiency (WUE) and other photosynthetic physiological factors and environmental factors were measured．The obtained data was analyzed by correlation analysis，path analysis and stepwise multiple-regression analysis to explore the relationship between the net photosynthetic rate and physiological factors. [Result]The results show that: ①The daily variation of the Pn，E，ALMC，C of E. pseudowushanense took on" two peak type"，the Pn was with an obvious midday depression phenomenon at noon. ②The Pn and ALMC of E. sagittatum were significantly higher than E. pseudowushanense. ③The correlation analysis，path analysis and stepwise regression analysis showed that ALMC，Ci might played important role in the Pn and ranked as ALMC ＞ Ci in two species. [Conclusion] In the actual production, two kinds of Epimedium should adopt different cultivation strategies.