Objective To quantitative the changing information of estrogen receptor β gene which was in tissue and organ of sex gland during oestrus and dioestrus of Beagles,and to show the different expression situation of hypothalamus-pituitary-gonad axis during oestrus and dioestrus, and providing the basic of theory to research deeply the mechanism of heat of Beagles. Methods As the key gene in regulation reproduction, ERβ gene is located in hypothalamus-pituitary-gonad axis, so using Beagles which was in oestrus and dioestrus, and extract the RNA from hypothalamus、pituitary、ovary and uterus respectively,after reverse transcription we detected the expression of ERβ gene by real-time quantitative PCR. Results The expression of ERβ gene mRNA from ovary、uterus、pituitary、hypothalamus of Beagles which was in dioestrus was 0.35 times, 0.17 times, 0.44 times and 0.43 times than the expression of ERβ gene mRNA from ovary, uterus, pituitary, hypothalamus of Beagles which was in oestrus. Conclusion The expression of ERβ gene was up-regulation in hypothalamus-pituitary-ovary axis of Beagles which was in oestrus.