〔Abstract〕 Objective To study the expression of galactose agglutinin-1(galectin-1) in endometrium of Hashimoto's thyroiditis rats during estrous cycle. Methods A total of 40 female mice aged 8～9 weeks were selected and divided into observation group and control group by random number table method, with 20 mice in each group. In the observation group, pig thyroglobulin was injected subcutaneously at the tail root to establish Hashimoto's thyroiditis model. Mice serum thyroglobulin antibodies(TgAb), thyroid peroxidase antibody(TPOAb), triiodothyronine(T3),tetraiodothyronine(T4), thyroid stimulating hormone(TSH) level of two groups were compared respectively. The endometrial thickness,galectin-1 mRNA expression, and the average optical density(AOD) of galectin-1 protein in each period of estrus cycle were also compared. The levels of tumor necrosis factor-α(TNF-α) and interleukin-17 A(IL-17 A) were compared between the two groups. Results Compared with the control group, serum TgAb and TPOAb levels in the observation group increased(P<0.05), and there was no statistically significant difference in thyroid hormone levels(P>0.05). In the estrous phase, the endometrial thickness increased(P<0.05) while the expression of galectin-1 protein decreased(P<0.05). The mRNA level of galectin-1 decreased(P<0.05) during the estrous cycle, and the expressions of TNF-α and IL-17 a in the uterine tissue homogenate decreased(P<0.05). Conclusion The endometrium of Hashimoto's thyroiditis rats becomes thicker and the content of galectin-1 decreases during estrus. Uterine tissue homogenate TNF-α and IL-17 a decrease.