This invention discloses uses for estradiol in preparing anti-small cell lung cancer and/or ovarian cancer and/or osteosarcoma products. This invention provides uses for estradiol in preparing anti-small cell lung cancer and/or ovarian cancer and/or osteosarcoma products. From carrying out cancer drug repositioning for the FDA- and CFDA-approved drug estradiol, experiments for this invention show, based on screening of non-anti-cancer drugs for various cancer cell lines (tissue types) and mutation sites, that estradiol has a new use as an anti-small cell lung cancer and/or ovarian cancer and/or osteosarcoma medication, thus achieving a new purpose for an old drug.
