Abstract: Objective To compare the osteogenic differentiation of dental pulp stem cells (DPSCs) induced by bone morphogenetic protein-9 (BMP-9) and mineralizing culture medium, and to find out a relatively ideal inducing method. Methods DPSCs cultured with appropriate concentration of BMP-9 were made as BMP-9 group, and those cultured in mineralizing culture medium were made as mineralization medium group. The morphological changes of DPSCs were observed under the inverted phase contrast microscope; MTT was used to test the cell growth curves; a Alizarin red staining was used for detecting the mineralization nodules; reverse transcription polymerase chain reaction (RT-RCR) was used for detecting the expression of osteogenesis related genes including bone sialoprotein (BSP), Runt-related transcription factor 2 (Runx-2), collagen-1 (Col-1) and osteocalcin (OCN). Results The results of MTT showed that BMP-9 and mineralizing culture medium could promote the proliferation of DPSCs, and the promotion of both groups was close to each other. The result of Alizarin red staining showed that mineralization nodules were formed after being induced by BMP-9 or mineralizing culture medium for 28 days, and the number as well as sizes of mineralization nodules in both groups were similar. The expression of osteogenesis related genes in both groups was positive after 14 days’ inducing cultivation, and the expression levels of both groups were close. Conclusion The capabilities of BMP-9 and mineralizing culture medium in inducing DPSCs’ osteogenic differentiation were similar.