Objective To investigate the efeects of microRNA(miR)-103a-3p regulates tumor protein 53-regulated inhibitor of apoptosis 1(TRIAP1) on osteoblast differentiation and bone mass in ovariectomized mice.    Methods MC3T3-E1 cells were divided into normal group, miR-103a-3p-NC group, miR-103a-3p mimic group, miR-103a-3p mimic + TRIAP1-NC group, miR-103a-3p mimic + TRIAP1 mimic group. mRNA expression of miR-103a-3p, TRIAP1, P53 were detected by Real-time PCR; Cell proliferation and apoptosis were detected by MTT test and flow cytometry; cytoskeleton and mineralization of cells were detected by F-actin immunofluorescence staining and alizarin staining; alkaline phosphatase(ALP) activity was detected by ELISA. 24 female mice were divided into sham group, osteoporosis(OP) group, miR-103a-3p antagonist-NC group, miR-103a-3p antagonist group(six in each group), extract bilateral ovaries to establish an OP model, sham group mice only isolated fat around ovarian tissue. mRNA expression of miR-103a-3p, TRIAP1, P53, ALP, osteocalcin(OCN), osteopontin(OPN) of bone tissue were detected; microCT detect bone mineral density (BMD), bone mineral content (BMC); haematoxylin eosin staining was used to observe pathological changes of bone tissue.   Results After miR-103a-3p mimic was transfected into cells, the miR-103a-3p and P53 expression increased, TRIAP1 expression decreased, cell proliferation decreased, apoptosis increased, F-actin expression decreased, the number of calcium nodules decreased, and ALP enzyme activity decreased (P<0.01); however, after TRIAP1 mimic was additionally transfected into cells, the above result  caused by miR-103a-3p mimics were significantly reversed (P<0.01). In OP group, the miR-103a-3p and P53 expression in bone tissue increased, the TRIAP1, ALP, OCN and OPN expression decreased, BMD and BMC were decreased, and bone tissue construct was damaged(P<0.05); in miR-103a-3p antagonist group, the miR-103a-3p and P53 expression in bone tissue decreased, TRIAP1, ALP, OCN, OPN expression increased, BMD and BMC increased, and bone tissue construct was improved (P<0.05).   Conclusion MiRNA-103a-3p mediate TRIAP1/P53 to inhibit proliferation and mineralization of osteoblast, while miR-103a-3p antagonistic treatment reduce bone loss in OP mice.