Objective To observe the distribution and morphologic variation of micrangium in diabetic rat’s femoral head and to probe into the difference of the expression of VEGF mRNA at the different time and the effect of the variation of the aldose reductase(AR) activity on the femoral head structure as well as micrangium lesion. Methods To set up the diabetic rat’s model with STZ, we divided the rats into three normal groups: CON1, CON2 and CON3 and three diabetic groups：DM1, DM2 and DM3, ten rats in each group. The structure of femoral heads of different group rats was observed under light microscope. The expression of coagulation factor Ⅷ was detected with immunohistochemistry. The density of micrangium was measured by infusion with ink. We also observed the expressive intenstiy of VEGF mRNA EM>in situ/EM> hybridization and analysised the activity of AR by making biochemical detection of the tissue homogenate of femoral head of the rat in each group. Results The diabetic rats’ femoral heads developed with the course of illness，the bone trabecula became thin and few,the marrow cavities enlarged.The expression of coagulation factor Ⅷ rose，the microvessel density enlarged.The expression of VEGF mRNA in vascular of the marrow cavities endothelial cells rose，and the activity of AR was enhancement（EM>P/EM><0.05）.Conclusion In the early period of diabetic rat’s femoral head t