Objective  The development and estimation of an animal subacute aging model induced by D  galactose were reported in the paper.Methods  The experiment was conducted on the 2.5  month  old SD rats injected with D  galactose 300?mg·kg    -1  ·d    -1   or 500?mg·kg    -1  ·d    -1   for 56 days by intra  peritoneum.The level of SOD,MDA,CH and TG were measured and the weights of rats thymus,spleen and ovaries of female rats was weighed.Results  The weights of male rats in group   500?mg·  kg    -1  ·d    -1   were lower than that of the rats of control group without D  galactose (  P  <0.01),and the serum SOD activity was lower too(  P  <0.05),but the content of serum MDA were higher.And the result indicated that the ratio of rats thymus weight with body weight was reduced (  P  <0.01) and that of spleen weight with body weight was increased in group 500?mg·kg    -1  ·d    -1   compared with control group.There were no significant differences between the indexes of female rats that were given D  galactose 500?mg·kg    -1  ·d    -1   and the female rats in control group expect that the serum SOD activity was higher than the latter (  P  <0.05).And 54.5% of the female rats that were given D  galactose 500?mg·kg    -1  ·d    -1   had ovaries cyst.Conclusion  Our results show that the rat model of subacute aging can be established by intra  peritoneum injection of D  galactic and the male rats are the first choice animals.