To study the transforming growth factor beta (TGF-β) signaling pathway in interactions with estrogen receptor alpha (ERα) signaling pathway mediating the growth of human uterine leiomyoma (UL) activated by phenolic environmental estrogens (EEs). The subcultured UL cells were used to determine the validation of TGF-β3 for the viability of human UL cells using CCK-8 assay, mRNA expressions of ERα, and c-fos by quantitative reverse transcription polymerase chain reaction method, and expressions of p-Smad3, SnoN, and c-fos proteins by Western blot assay in each treatment group. Compared with each of EEs or TGF-β3 treatment, slightly decrease in the proliferation rate of UL was detected in the coexistence of each EE with TGF-β3. Interestingly, mRNA expressions of ERα and c-fos reduced in the setting of coexistence of TGF-β3 and EEs. Somehow, the expression of p-Smad3 and c-fos proteins significantly decreased in each of E2, bisphenol A (BPA), nonylphenol (NP), and octylphenol (OP) group, as well as the expression of SnoN protein significantly reduced only in BPA and NP groups, followed by TGF-β3 treatment. With the overlaid action of ICI 182,780, the expression of p-Smad3 protein significantly increased in OP group, but slightly increased in E2, BPA, NP, and OP groups. However, compared with the control group, the expression of SnoN and c-fos proteins significantly decreased in the same setting. Both ERα signaling pathway and TGF-β signaling pathway have different roles in governing UL cell proliferation. The phenolic EEs can be a promoter to the proliferation of UL cells, which is mediated by ERα signaling pathway and cross-talked with TGF-β signaling pathway.