17-Estradiol (E2), a typical natural estrin, was chosen to study the mixed effect of Cd with natural estrins.The aim is to understand the impact of Cd on human health.Human breast cancer cell MCF-7 increase examination was used to examine the estrogenicity.The results showed that Cd had estrogencity, but E2 dramatically decreased its effect.Cell cycle analyses showed that Cd, E2, and their mixture all increased the ratio of cells in the DNA synthetic phase and therefore promoted cell proliferation.Cell proliferation pathway analyses showed that Cd, E2, and mixture significantly reduced the expression of ERα protein in the cell.The rivalry effect between E2 and Cd was mainly from the MAPK signal transduction pathway.E2 and Cd both promoted the expression of Ki67 protein and prolification-related protein, but the mixture significantly reduced the expression of Ki67.