Objective: To investigate the effect of honokiol on the epithelial-mesenchymal transition (EMT) process of prostate cancer cell line PC3 and to explore its possible mechanism. Methods: Different concentrations of honokiol (0, 10, 20, 40 μmol/L) were applied to PC3 cells for 24 hours. The effects of honokiol on cell migration and invasion were examined by cell scratch test and Transwell chamber test. After treatment with different concentrations of honokiol (0, 10, 20, 40 μmol/L) in PC3 cells for 48 hours, the expression of E-cadherin, N-cadherin, vimentin and β-catenin in PC3 cells was detected by Western blotting. The effect of honokiol on the relative expression of β-catenin and MMP-9 mRNA in PC3 cells were detected with RT-RCR. Results: Compared with the control group (honokiol 0 μmol/L), the migration and invasion ability of PC3 cells treated with honokiol was greatly reduced, and the expression of N-cadherin, vimentin and β-catenin protein in cells decreased significantly. The expression of E-cadherin protein was significantly increased, and the relative expression of β-catenin and MMP-9 mRNA was significantly decreased, and the above results were dose-dependent. Conclusion: Honokiol can inhibit the migration and invasion of PC3 cells, which may be caused by inhibiting the activity of Wnt/β-catenin signaling pathway and thereby reducing EMT activity.