Objective To study the role of transcription factor Yin-Yang 1 (YY1) upregulating the expression of programmed death ligand 1 (PD-L1) in promoting immune escape of gallbladder cancer. Methods Immunohistochemistry was used to detect the expression level of YY1 protein in gallbladder cancer, adjacent, and normal gallbladder tissues. The levels of YY1 were measured by Real-time quantitative PCR (qRT-PCR) in normal human gallbladder epithelial cell line HGBEC and human gallbladder cancer cell lines GBC-SD, SGC-996, and IH-GB1. YY1 siRNA-1675 was transfected into GBC-SD cells. The experiment included BC, YY1 siRNA NC, and YY1 siRNA-1675 groups. The levels of PD-L1, CD69, and CD25 and the apoptosis rate of human T lymphocytes were measured by flow cytometry. The levels of interleukin (IL)- 2, IL-4, IL-10, and interferon-gamma (IFN-γ) in supernatants were determined by enzyme-linked immunosorbent assay. The PROMO website was used to predict the potential target genes of YY1, which were verified by dual luciferase reporter assays. Results Compared with normal tissues, the expression rate of YY1 in paracancerous and gallbladder cancer tissues was increased significantly (P < 0. 05). Compared with adjacent tissues, the expression rate of YY1 protein in gallbladder cancer tissues was increased significantly (P < 0. 05). Compared with HGBEC cells, YY1 levels in IH-GB1, SGC-996, and GBC-SD cells were significantly higher (P < 0. 05), and the level of YY1 in GBC-SD cells was the highest. Therefore, GBC-SD cells were used in subsequent experiments. Compared with BC and YY1 siRNA-NC groups, the levels of IL-2, IL- 4, IL-10, IFN-γ, CD69, and CD25 in the YY1 siRNA-1675 group were significantly higher (P < 0. 05), while the levels of YY1 and PD-L1 and the apoptosis rate of human T lymphocytes were decreased significantly (P < 0. 05). The PROMO website predicted that PD-L1 was a target gene of YY1, and dual luciferase reporter assays confirmed that PD-L1 was a target gene of YY1. Conclusions Downregulating the level of YY1 inhibits the expression of PD-L1, which may inhibit the immune escape of gallbladder cancer.