In order to explore the changes in reproductive hormones in female blue foxes (Alopex lagopus) during estrus and gestation, 11 breeding individuals were selected and their serum levels of estradiol (E2), luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone (P) and prolactin (PRL) were determined by radioimmunoassay (RIA). The results showed that the serum concentrations of follicle stimulating hormone and luteinizing hormone in estrus and gestation were at a relatively stable level and showed a fluctuating secretion pattern. The maximum values in the two periods were 2.18 ± 0.69 U/L and 8.82 ± 1.83 U/L, respectively. The serum concentration of estradiol in estrus and gestation was also at a relatively stable level, with the maximum value at 27.73 ± 23.19 ng/L on the fist day of estrus, but the overall values were not significantly different from each other (P > 0.05). Progesterone remained at a high level during estrus, with the maximum value synchronizing with estradiol 2.41 ± 1.35 μg/L on the third day, which continued to decline during gestation, and reached the lowest point on the day of delivery 0.13 ± 0.14 μg/L. The overall values were significantly different from each other (P < 0.05). Prolactin first decreased during estrus, the lowest value was 0.15 ± 0.04 U/L, and then increased on the 3nd day. The level remained high during pregnancy, and reached the highest level 0.21 ± 0.05 U/L at the time of delivery, with no significant difference in the overall value (P > 0.05). The dynamic changes of each index during this period were preliminarily explored to provide reference data for reproductive physiology of blue fox.