Abstract: Juvenile zebrafish were used to screen the active components of Lycii Fructus for improving osteoporosis. The screening results were further verified by zebrafish adult osteoporosis model and the action mechanism was explored. Prednisolone was used as the inducer to build osteoporosis models of juvenile and adult zebrafish, and 9 groups of samples of different extracts and chemical parts of Lycii Fructus were given. Alizarin red staining was applied for observing the scale matrix mineralization and bone resorption. The activities of osteoblasts and osteoclasts were detected using alkaline phosphatase (ALP) and tartrate resistant acid phosphatase (TRAP/TRACP) staining. The expressions of bone metabolism-related genes alp, osteoprotectin (opn), osteoblast specific transcription factor (sp7), cathepsin K (ctsk), tracp, and Runt family transcription factor 2b (runx2b) in each group were determined using quantitative polymerase chain reaction. The results showed that all components of Lycii Fructus improved the formation area of the first vertebrae, the staining light density value, and the number of vertebrae joints in juvenile zebrafish and the Lycium barbarum polysaccharide (LBP) treatment group exerted the best effect. In addition, LBP prevented the formation of bone resorption lacunae in zebrafish scales, increased ALP activity, decreased TRAP activity, up-regulated the alp, sp7, and opn genes, and lowered the expressions of ctsk and tracp genes. In conclusion, LBP regulated the activity of osteoblasts and osteoclasts, reduced bone resorption, promoted bone formation and enhanced bone density, which might be the main anti-osteoporosis active fraction of Lycii Fructus. This study provided modern scientific evidence for the scientific connotation of the traditional effect of "strengthening bones and muscles" of Lycii Fructus, provided the reference for the evaluation of the anti-osteoporosis activity of traditional Chinese medicine based on zebrafish adult model, and provided beneficial enlightenment for the bone health needs of the aging society population.