The present study was conducted to discuss the effects on genetically modified soybeans on the level of mRNA and protein in StAR gene in male rat, and aimed to provide a scientific basis for the security of transgenic soybeans. Thirty male SD rats were randomly divided into GM group and CK group. The GM group were fed with transgenic Roundup Ready soybean containing CP4-EPSPS gene, and the CK group were fed with non-transgenic soybean. Three rats of every group were killed at 30 d, 60 d and 90 d, respectively. Viscera index (testes and epididymides) was calculated. RT-PCR was used to measure the expression of StAR gene, and ELISA was used to analysis the expression of StAR protein. The morphology and color of testes and epididymides of the GM group and CK group were observed. No significant differences were found in size and testis coefficient. Epididymis coefficient were no significant difference（P>0.05）except 30 d group. The average expression of StAR gene and protein in GM and CK group (30 d 60 d and 90 d) was detected, and no significant differences between the two groups at the same time were found. The results suggested that feeding transgenic soybean for 30 d showed no damages to occurrence of testes and epididymides in rat, and the expression of StAR gene and protein were no difference either.