Abstract: This study was conducted to evaluate the cryoprotective function of sugars in two freezing media (TTE and TEST) by comparing the spermatozoa morphologic change of rhesus monkey before and after cryopreservation using transmission electron microscopy.The results showed that the structure of acrosome integrity,nuclear and tail of most spermatozoa cryopreserved with TTE was similar with that of fresh spermatozoa,except for the slight swell of plasma membrane.However,in spermatozoa cryopreserved with TEST,the plasma membrane were fluctuated,swelled and broken,the acrosome integrity and nuclear were damaged,and the structure of tail were changed significantly.It demonstrated that TTE is a suitable freezing media for rhesus monkey spermatozoa cryopreservation.Sugars exert cryoprotective roles by protecting the intact of plasma membrane and acrosome integrity,but the protective roles of sugars are significant different.