Objective To evaluate anti-osteoporotic activity of icariin and Epimedin C monomer under the same molarity in predinsolone-induced osteoporosis zebrafish. Methods Zebrafish larvae after 4-day fertilization were divided into group S [0. 5% dimethyl sulfoxide (DMSO) , A (25 μmol/L prednisolone, 0. 5% DMSO), B (2 IU/L salmon calcitonin, 25 μmol/L prednisolone,0. 5% DMSO), C (1. 5 1,mol/L icariin, 25 μmol/L prednisolone, 0. 5% DMSO) , D (15 μLmol/L icariin,25 μmol/L prednisolone, 0. 5% DM- SO), E (150 μmol/L icariin, 25 μmol/L prednisolone, 0. 5% DMSO), F (1. 5 μmol/L Epimediri C, 25 μmol/L prednisolone, 0. 5% DMSO) , G (15 μmol/L Epimedin C, 25 μmol/L prednisolone, 0.5% DM- SO) , H (150 μmol/L Epimedin C, 25 μmol/L prednisolone, 0. 5% DMSO). All culture solution contained 0. 5% DMSO. All the young fishes were grown in a 24-well plate. The culture medium was changed every day. They were cultured in a incubator box at 28. 5 °C and killed at day 9. Zebrafish skeleton was stained with alizarin red. The stained Zebrafish ventral skull was observed using microscope, and mineralized area was quantitatively analyzed. Results Compared with group S, accumulative integrated optical densi- ty(IOD)of the mineralized area significantly decreased in group A (P <0. 01) ; accumulative IOD of the mineralized area significantly increased in group B (P <0. 01). The accumulative IOD of the mineralized area showed weakly increasing tendency in group C, D, and E along with increased concentration (P < 0. 05). Compared with group A, accumulative IOD obviously increased in group B with statistical difference (P <0. 01) , but with no statistical difference as compared with group C or group D (P >0. 05). Statistical difference existed in accumulative IOD between group A and group E (P <0. 05). The mineralized area showed increasing tendency in group F and group G along with increased concentration (P <0. 05), and accumulative IOD obviously increased as well (P <0. 05). No Zebrafish embryo survived in group H. There was no statistical difference in Zebrafish embryo survival among group E, F, or G (P >0. 05). The staining of Zebrafish skull was clearly seen in group S, with vertebrae and bilateral branchial skeleton clearly seen. The intensity of staining in the same area was obviously attenuated in group A. The osteo- genesis was speeded up under the same condition in group B, with obviously enlarged mineralized area and more darkly stained bone tissue. The mineralization of skull was gradually increasing during the stai- ning process in group C, D, E, F, and G. The mineralized area and the intensity of staining were gradually enhanced, and changes of vertebrae were most obviously seen in group C, D, E, F, and G, but they were not arrived at the stained intensity level in group B. Conclusions Osteoporosis Zebrafish model is a simple and efficient model for screening bioactive ingredients of Chinese herbs. The activity of Epimedin C at low concentration was better than icariin in this model. But possible toxicity of Epimedin C at high concentration needs to be further studied.