Objective To investigate the effects of BDE-209 exposure on the sperm quality of prepubertal male rats. Methods Twenty four 3-week old SD rats were randomly divided into the control group and three BDE-209 groups. BDE-209 groups were given BDE-209 of 2, 10, and 50 mg/kg by the intragastric injection for one month after 28 d of birth. The control group was given pure corn oil by the intragastric injection for one month. Rats were sacrificed on Day 63. The morphological changes of sperms were observed. The deformity rate of sperms was calculated and kinesis parameters were measured. Results Typical morphological changes such as banana-shaped, no hook, and fat head were observed in BDE-209 groups. The deformity rates of BDE-209 groups were (10.50±3.987)‰, (11.50±6.775)‰, and (10.83±4.401)‰, respectively. The deformity rate of control group was (4.00±3.688). The deformity rates of BDE-209 groups were significantly higher than that of the control group (P<0.05). The differences of kinesis parameters of BDE-209 groups and the control group were not statistically significant (P>0.05). Conclusion Exposure to BDE-209 has certain influence on the sperm quality of male SD rats.