Objective:To investigate the effect of tissue engineered bone of the chitosan/phosphonic chitosan sponge combined with human umbilical cord mesenchymal stem cells (HUMSCs) on repairing bone defects. Methods:First,The tissue engineered bone was constructed in vitro;Second,New Zealand rabbit model with bone defect were divided into groups A,B,and C. The complex sponge was implanted into bone defects in group A;cell scaffold composites were implanted in group B;and group C was as control. The defective bone specimen was collected at 4th,8th,12th week after implantation sugery. The gross and histological changes and the imaging of bone specimen were observed. Results:After 12 weeks,new bone have completely filled the bone defects in group A. Moreover,bone stump have been connected by some cortical bone. While part of porosis can be found in group B,but no continuous sclerotin was observed. Only little porosis can be found in group C. Conclusion:The tissue engineered bone by combining the HUMSCs with chitosan/phosphonic chitosan sponge has the potential of osteogenic ability in rabbit,and can become material substitution for bone transplantation.