Objective: To determine whether p27 plays an important role in modulating bone mass and bone turnover. Methods: We used 8-weeks-old p27 homozygote （p27-/-） mice and WT littermate mice. Firstly， we performed bone marrow ablation （BMX） on both tibia and femur， and then we compared the difference between osteogenesis and bone turnover of the different groups by radiography and pathologic histology. Finally， we detected the difference of ostosis and bone turnover between groups on the 3rd/7th/11th/14th day after BMX respectively. Results: Three days after BMX， the bone mass of both WT and p27-/- littermate showed no new osteogenesis. While compared to WT littermate， on the 7th/11th/14th day after BMX， the new osteogenesis in p27-/- mice increased significantly. Further study showed that the number of osteoblasts and the positive area of type I collagen increased significantly. However， the number of osteoclasts and the positive area of osteoclasts decreased markedly. Conclusion: The BMX of p27 gene knockout mice study proved that p27 could reduce the bone mass and inhibit bone turnover by suppressing the osteogenesis of osteoblasts and promoting the bone resorption of osteoclasts.