Objective  To investigate the effects of dams-offspring separation on anxiety-like behaviors of dams, and if these anxiety-like behaviors of dams  are associated with estrogen receptorα（ERα）and β（ERβ）in some brain regions.   Methods  Thirty C57BL/6 J female mice were divided into three groups, control group（CG，n=10，non-isolated group）, short-term separation group（SG，n=10, dams were separated from their offspring for 15 minuts per day from the second day to the tenth day after childbirth）and long-term separation group（LG，n=10, dams were separated from their offspring for 3 hours per day from the second day to the tenth day after childbirth）. Anxiety-like behaviors of dams were evaluated in an open-field（OF）and elevated plus-maze test（EPM）. The level of ERα- immunoreactive neurons（ERα-IRs）and ERβ- immunoreactive neurons（ERβ-IRs）in three brain regions including medial preoptic area（mPOA），hypothalamic ventromedial nucleus（VMH）and medial amygdaloid nucleus（MeA）were analyzed.   Results  In OF，compared to CG group and SG group, LG group had significantly less time in center area, crossing number and total distance（P<0.001），there were no significant difference between the CG group and SG group（P>0.05）. In EPM，compared to CG group and SG group，LG group had significantly less percentage of time, distance in open arms and total distance（P<0.001）. Compared to CG group and SG group，LG group had significantly less ERα-IRs and ERβ-IRs in mPOA, VMH，and MeA（P<0.01）.   Conclusion  Dams that are long-termly separated from their offspring may have anxiety-like behavior, and this behavior may be related to the significant reduction of ERα and ERβ in these brain regions.