To investigate the effects of resveratrol (RSVL) on epithelial-mesenchymal transition (EMT) and biological behaviors of gastric cancer cells. SGC-7901 cells were treated with RSVL, followed by TGF-β1 treatment for induction of EMT. Cell proliferation was tested by MTT assay, migration and invasion by Transwell and scratch assays, and Hippo-YAP signaling pathway activation by immunofluorescence. The RNA and protein expressions of E-cadherin, Vimentin, N-cadherin, and Snail were detected by qPCR and Western blot. A tumor model was constructed to examine the effect of RSVL on gastric tumor growth. RSVL inhibited the migration, invasion, and growth of gastric cancer cells in concentration- and time-dependent manners. RSVL inhibited TGF-β1-induced EMT of gastric cancer cells, which might relate to inactivation of the Hippo-YAP pathway. In the mouse tumor model, RSVL inhibited the EMT process by suppressing the Hippo-YAP pathway. RSVL inhibited EMT of gastric cancer cells probably by weakening the Hippo-YAP signaling pathway.