Abstract: To study the osteoprotective effect of 1,2,3,4,6-pentyl-O-galloyl-beta-D-glucose (PGG) its anti-osteoblast apoptosis related mechanism was investigated. A model of zebrafish osteoporosis induced by prednisolone (Pred, 25 μmol·L^-1) was established in vivo, and calcein staining was used to detect the effect of PGG on the bone area of zebrafish. Bone marrow mesenchymal stem cells were cultured in vitro, and the number of calcified nodules was observed by alizarin red staining, and the relevant indexes of osteoblast differentiation runt-related transcription factor 2 (Runx 2), osteocalcin (OCN) mRNA level were detected by qRT-PCR. The osteoblast cell line MC3T3-E1 cells was cultured in vitro, and 400 μmol·L^-1 hydrogen peroxide (H₂O₂) was used to intervene the injury to detect the effect of PGG on osteoblasts under oxidative stress. The effect of PGG on osteoblast activity was detected by MTT assay. The effect of PGG on apoptosis was observed by Hoechst 33342 staining. Western blot was used to detect the expression of Bcl-2, Bax, nuclear factor erythroid-2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). DCFH-DA fluorescence staining for detection of reactive oxygen species (ROS) levels. JC-1 staining was used to detect mitochondrial membrane potential levels. The results showed that PGG could significantly increase the vertebral area of the zebrafish model when compared with the model group. On the 14 th day of osteoblast differentiation, the number of calcified nodules in the PGG group was significantly increased when compared with the control group and the mRNA levels of Runx 2 and OCN were also significantly increased. In addition, under oxidative stress, PGG could increase osteoblast viability, significantly reduce the number of apoptotic cells, and increase the ratio of Bcl-2/Bax. Fluorescence staining results show that PGG decreased intracellular ROS fluorescence density and increased mitochondrial membrane potential. Western blot data showed that PGG could promote the expression of Nrf2 in the nuclear and enhance the expression of downstream protein HO-1. In conclusion, PGG could improve osteoporosis in zebrafish, and this effect may be related to the regulation of Nrf2/HO-1 signaling pathway to improve mitochondrial dysfunction, anti-oxidative stress in osteoblast apoptosis and promote bone formation. This study provides new ideas and clues for the discovery of anti-osteoporosis drugs.