Objective：This study aims to observe the effects of γ-Fe₂O₃-loaded chitosan porous sponge on the proliferation and early osteogenic differentiation of rat bone marrow mesenchymal stem cells(rBMSC). 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 rBMSC 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 alkaline phosphatases(ALP)staining and activity detection. Real - time fluorescence quantitative reverse transcription PCR was used to detect the expression of ALP，bone morphogenetic protein 2(Bmp2)，collagen I(Col1)and Runt-related transcription factor 2(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 rBMSC. ALP staining and activity detection 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 with γ-Fe₂O₃ added concentration 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 rBMSC，and loading γ-Fe2O3 at concentration of 5% and 10% can promote the formation of mineralization in the late stage of osteogenic differentiation of rBMSC.