Objective To analyze the effect of mesporous calcium silicate (m-CS)/calcium sulfate cement (CSC),m-CSC for short,in bone defect repair.Methods Setting time and compressive strength of the m-CSC (15 m-CSC as group Ⅰ and 30 m-CSC as group Ⅱ) were tested.CSC was used as the control.Cement samples were immersed in Tris-HCl solution,andin vitro degradation of the m-CSC was measured.Cell morphology and cell proliferation as well as differentiation on the samples were assessed.The cements were implanted into the traumatic femoral defects in rabbits,and the in vivo degradability and osteogenesis of the cements were investigated by histological evaluation after implantation for 4,8 and 12 weeks.Results Addition of m-CS into CSC prolonged the setting time (7.8 min in group Ⅰ and 10.5 min in group Ⅱ),obviously longer than 3.7 min in control group and did not have obvious effect on compressive strength of the cements.Weight loss of m-CSC solution was obviously lower (61.8 wt％ in group Ⅰ and50.3 wt％ in group Ⅱ),compared to70.4 wt％ in control group,pH value in group Ⅱ decreased from 7.40 to 7.26,while decreased from 7.40 to 6.86 in control group,m-CSC could promote cell proliferation and differentiation compared to CSC.At postoperative 12 weeks,histological sections showed massive new bony tissue (55.2％) in group Ⅱ,obviously higher than 25.6％ in control group.Conclusion m-CSC exhibits good biocompatibility,degradability and osteogenesis,and can promote bone regeneration in bone defect repair.