The aim of this study is to investigate the effect and mechanism of 17 β-estradiol (E2) on oxidative stress in the osteoblasts. An oxidative stress-induced damage model was established using H2O2 in MC3T3-E1 cells, and H2O2-induced cells were treated with E2. The results indicated that E2 attenuated oxidative stress in H2O2- induced MC3T3-E1 cells. In addition, H2O2 upregulated the expression of miR-320-3p and downregulated that of RUNX2, but these changes were counteracted by E2. Thereafter, we verified the interactive relationship between miR-320-3p and RUNX2. Then, H2O2-induced MC3T3-E1 cells were transfected with miR-320-3p mimics or inhibitors and treated with E2. The results indicated that miR-320-3p inhibition suppressed H2O2- induced inflammation, apoptosis, and oxidative stress and promoted the osteogenic differentiation of MC3T3- E1 cells by regulating RUNX2, ALP, and OCN, and this effect was further strengthened by E2. In conclusion, the findings suggest that E2 alleviates oxidative damage in osteoblasts by regulating the miR-320/RUNX2 signaling.