Objective：To study the effects of γ-Fe2O3-loaded chitosan porous sponge on the proliferation and early osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs). Methods：Chitosan sponges loaded with γ-Fe2O3 at concentrations of 1%, 5%, 10% and 20% were prepared by freeze-drying and cross-linking, and blank control group was prepared. Scanning electron microscopy and confocal microscopy were used to evaluate the adhesion and proliferation of rBMSCs on the sponges. Cell proliferation at 1, 3, 5 and 7 days was detected by CCK?8. The early osteogenic differentiation of rBMSC at 7 and 14 days was evaluated by ALP staining and activity detection. Real-time fluorescence quantitative reverse transcription PCR was used to detect the expression of alkaline phosphatases (Alp), bone morphogenetic protein 2 (Bmp2), collagen I (Col1) and core binding factor alphal 1 (Runx2) after 7 and 14 days of osteogenic induction. The mineralization of extracellular matrix at 21 and 28 days was assessed by alizarin red staining quantitative method. Results：CCK?8 results showed each group added with γ-Fe2O3 promoted the proliferation of rBMSCs. ALP activity detection and staining results showed the addition of γ-Fe2O3 can improve the activity of ALP. The results of real-time fluorescence quantitative reverse transcription PCR showed that the addition of γ-Fe2O3 can promote the expression of osteogenic indexes Alp, Bmp2, Col1 and Runx2 . The quantitative detection results of alizarin red staining showed that the amount of mineralization in the groups of 5% and 10% was higher than that in the control group. (P < 0.05) Conclusion：The chitosan porous sponge loaded with γ-Fe2O3 promoted the proliferation and the early indicators of osteogenic differentiation of rBMSCs, and that at concentration of 5% and 10% can promote the formation of mineralization in the late stage of osteogenic differentiation of rBMSCs.