Cadmium, as an inorganic pollutant, its toxic effects on mammals were widely studied, while less attention was paid on its endocrine disrupting effects. In this paper, the effects of CdCl2 on mice uterine-ovary wet weight, modulation of ER (estrogen receptors) mRNA level and their relation were studied. It showed that uterus-ovary wet weight, the expression of ER(subtype) and ER (subtype) were of significant difference in 930µg/kg•bw CdCl2 dosing group compared with the control. However, only up-regulation of ER was detected in 9.3µg/kg•bw CdCl2 dosing group. It suggested that the high expression of ER might protect mice from increasing of uterus-ovary wet weight. For CdCl2 estrogenic activity, the ER expression mechanism and ER-responsive elements pathway need further examination.