Objective To explore the mechanism by which puerarin stimulates osteogenesis and bone formation through the ERK1/2 and p38 MAPK signaling pathways. Methods Adult osteoblasts (MC3T3-E1) cell culture was used in this study.The proliferative ability and the influence of growth curve of the cells after added different concentrations of puerarin were compared by MTT staining. The effect of puerarin on the differentiation of osteoblasts was assessed by measuring alkaline phosphatase activity and the effect of puerarin on bone formation was analyzed by measuring calcium deposition. Through the addition of ERK1/2 blocker PD8089 and p38 inhibitor SB203580, the mechanisms of involvement of the ERK1/2 and p38 MAPK signaling pathways in stimulating osteogenesis and bone formation were analyzed. Western blotting was used to detect the expression of bone morphogenetic protein-2 (BMP-2). Results Different concentrations of puerarin promoted the proliferation of osteoblasts to different degrees. The effect of puerarin at 0. 1 mol/ L was the most significant. The trend of proliferation was not pronounced on the first and third days compared with the level in the blank group, but significant differences emerged between the fifth and seventh days. Puerarin activated alkaline phosphatase activity and promoted the differentiation of primary osteoblasts. It also promoted calcium deposition and stimulated bone formation. After using the ERK1/2 blocker PD8089 or blocking the p38 MAPK signaling pathway with the inhibitor SB203580, cell proliferation, alkaline phosphatase content, and calcium deposition were lower than those of the puerarin group. The expression of BMP-2 in group puerarin (T) was higher than that of the control group ( P <0. 05), and that of group puerarin+PD 8089(T+PD)was lower than that of group T, while the amount of calcium deposition in the group puerarin+SB 203580(T+SB)was significantly lower than that in group T ( P <0. 05), and there was a decrease ( P <0. 05)in the BMP-2 expression compared with that in the control group. Conclusions In the cell cycle in bone, puerarin and the ERK1/2 and p38 MAPK signaling pathways play regulatory roles in bone differentiation and bone formation.