Objective:To investigate the expression of IQGAP3 in cholangiocarcinoma(CCA) and its clinical significance. Methods:RT-PCR and Western blot were performed to determine the levels of IQGAP3 in CCA tissues and CCA cell lines. Colone formation assay,CCK8 and EdU proliferation experiment were used to reveal the role of IQGAP3 in CCA cell proliferation in vitro. Western blot and phosphorylated proteinchip array were used to verify the possible mechanisms of IQGAP3 in regulating the proliferation of CCA cells. Results:IQGAP3 was overexpressed in the CCA tissues and cell lines. IQGAP3 promoted the proliferation of CCA cell lines in vitro. The expression of IQGAP3 was significantly correlated with tumor size,pathological grading and AJCC TNM staging in CCA patients combined with clinical sample data. Kaplan-meier survival analysis showed that the survival time of the CCA patients with high IQGAP3 expression was significantly lower than that those with low IQGAP3 expression. The expression level of IQGAP3 was positively correlated with the expression of WNK1. Conclusion:IQGAP3 was overexpressed in CCA and might promote the proliferation of CCA cells by up-regulating WNK1.