Estrogen receptors (ERs) are members of a superfamily of ligand-modulated nuclear receptors, which have been associated with an increased risk of cardiovascular diseases and breast cancer. Based on molecular docking studies, 1,4-dihydrothieno[3',2':5,6]thiopyrano[4,3-c]pyrazole-3-carboxamide derivatives as estrogen receptor inhibitors with a new scaffold , have been synthesized and tested for the antitumor activity on the ER expressing (ER dependent) human MCF-7 breast cancer cell line. According to the biological activity evaluation, compound 6a demonstrated the most potent antiproliferative activity (relative inhibitory rate: 100%). Several of these compounds exhibited moderate antitumor activity and worthy of further modification to obtain more potent anticancer candidate drugs.