Abstract: Frozen sperm of Tibetan mastiff were smeared and stained by Giemsa stain and eosin to observe sperm deformity.The results showed that the heads of sperm stained by eosin were stained moderately,and the sperm had a clear head,clear ridge and acrosome,and clear deformity of middle and tail part.Sperm deformity rates were not significantly different between the two staining methods.Because eosin stain can be prepared simply,eosin staining can be used as the optimal method to detect sperm deformity.