As a pro-inflammatory cytokine, Interleukin 17A (IL-17A) plays an important role in pathology of tumor microenvironment and inflammatory diseases. In this study, we intend to investigate the role of IL-17A on the metastasis of gallbladder cancer (GBC) and related mechanisms. The serum levels of IL-17A were associated with node metastasis and advanced stage. We also found the pro-invasion effect of IL-17A on GBC cells. When treated with IL-17A, the protein level of epithelial marker E-cadherin in GBC cells was significantly down-regulated, while the protein level of the mesenchymal phenotype marker vimentin was significantly increased. IL-17A increased the expression of transcription factor slug, the phosphorylation of ERK1/2 and the nuclear translocation of NF-kappa B/p50 and p65 in a concentration-dependent manner. Pretreatment of cells with U0126 could reverse the nuclear translocation of NF-kappa B/p50 and p65 and EMT induced by IL-17A. IL-17A promotes gallbladder cancer invasiveness via ERK/NF-kappa B signal pathway mediated epithelial-to-mesenchymal transition. As a new therapeutic targets and diagnostic marker, IL-17A may play an important role in the treatment of GBC.