In this study an experimental observation was made in the Chinese hamsters of Shanyi colony. The estrous cycle of a female hamster was about 4.0 days. During the estrus its vaginal smear was alkaline. Its gestational period was on average 20.05 days. A small black embolus appeared in the hymenal orifice, it serves as evidence of early pregnancy. Ia general, the hamsters became mature in sex when they were 55 days old, but the female were later than the male. An adult female hamster was on average 26.5g body weigth and its body longth was 8.8cm while an adult male hamster 32.5g and 9.9cm respectively. High generation inbreeding hamsters tended to become smaller in shape than the wild and their former generations.