Objective:To observe the change of the oxygen free radical and antioxygen level that existed in cavernous body of penis of diabetus mellitus(DM) rat with erection dysfunction(ED)

and observe the morphology change on the electron microscope to probe into the nosogenesis of DMED. Methods:To make the DMED model on rat by streptozotocin

breed for 12 weeks after it

then to determin the indexes about oxygen free radical and antioxygen level and ultrastructure of cavernous smooth muscle after anesthetize. Results:The level of oxygen free radical increased and antioxygen decreased

the blood capillary thrombogenesised

the chondriosome swelled and distend

the desmocyte activated

the nerve fiber medullary sheath degenerated

all those were observed in the DMED group

and had significant different with control group. Conclusion:The change of ultrastructure occurred in DMED rat induced by the oxygen free radical damage and decrease of antioxygen level

it has associativity with the aggravation of smooth muscle endodermis

the blood vessel endothelium

the nerve fiber and the chondriosome

it’s ONE OF the nosogenesis of DMED.And it suggested to use oxygen free radical scavenger may be relieve the change of ultrastructure and ED

it may be supply anthoer therapy pathway for DMED.