Abstract: The reproductive mechanism of canine is different from other animals. Its main characteristics include：the maturation of oocytes after ovulation, a delay in the implantation of embryo, rise of serum progesterone concentration before ovulation, similar concentration of serum progesterone between pregnant canine and non-pregnant canine, absence of pregnancy-specific proteins and production of placental external relaxin, etc. Because the progesterone concentration in blood plasma couldn′t reflect the function of luteum and the metabolism of progesterone, so the adjustment mechanism of canine pregnancy was not yet elucidated. The current situations of the relevant research on hormones that played main functions in the gestation period of canine and their effects on the endocrine were reviewed, so as to provide theoretical foundation for enucleating the regulation mechanism of endocrine in the gestation period of canine.