Abstract: Objective To study the injury of rats sexual system by alcohol and its effect on eugeny.Methods Various doses of alcohol were administered through gastric tube in rats.At the different time alchol had been given,the blood,sperm,and sexual organs of rats were taken to test the change in hormone,sperm quality and histology.Results When the rats had been given alchol with high doses and for a longer time,their relative gravity of testises and epididymis(mg/100g)were decreasd.The rate of sperm activity was much weaker than normal's(P<0.01).The propertion of living sperms was significantly less than normal's(P<0.01).The rate of the sperm deformity was higer than the norma's(P<0.01).The content of LH、FSH and T level in the serum was lower than the normal's.The histology of the sexual organ also have morphology changes.Conclusion Alcohol can cause sexual system injury and so,reducing alchol intaking is important too eugeny.