Leukemia inhibitory factor(LIF) is a glycoprotein with multiple activities, it expresses violently in most mice endometrium on 4-5 day of pregnancy,however the mechanism of LIF gene expression was not known completely. LIF gene expression was examined in endometrium of 168 mice and the concentrations of progesterone and estradiol were measured in their serum on 4-5 day. The expression of LIF gene was totally absent in 18 mice,and their concentrations of progesterone and estradiol in serum were significantly lower than the others. We discussed the relation between the expression of LIF gene with the concentration of two hormones. It was showed that the expression of LIF gene might be partly controlled by progesterone and estradiol.