Objectivet To explore the changes of biomechanical properties of cancellous aIlograft and its relationship with different biomechanical environment. Methodf Cancellous allograft was transplanted to each side of the midshaft diaphyseal ulnar of 40 rabbits. The left transplanted allograft underwent normal physiological load, while the right underwent lower load. Animals were kiIled and specimens taken for examination of bone mineral density, three-point-bending test and mean trabecular thickness. Results: Bone mineral density, maximal bending moment and mean trabecular thickness of graft were found to have been increasing constantly. At the sixteen week after transplantation, the above data of normal loaded graft is better than that of lower loaded graft (P<0.01,0.05,0.05 respectively). Conclusionf Changes of biomechanical properties of cancellous allograft shows more apparent correlation with the magnitude of load to which the graft would be subject.