Objective To explore the regulatory mechanism of miR-145-5p and MEST in gastric cancer epithelial cells. Methods The expression, correlation and target sites of miR-145-5p and MEST were analyzed. qRT-PCR and Western blot were used to detect the expression of miR-145-5p and MEST. The dual luciferase experiment was used to detect targeting relationship between miR-145-5p and MEST. The cell proliferation experiment, clone formation experiment, scratch experiment and Transwell experiment were used to detect the proliferation, metastasis and invasion ability of gastric cancer epithelial cells. Results Compared with normal gastric epithelial cells, the expression of miR-145-5p in gastric cancer epithelial cells was low, while the expression of MEST was high. There was a targeting relationship between miR-145-5p and MEST, and the overexpression of miR-145-5p could weaken the effect of MEST on cancer cell proliferation, metastasis and invasion. Conclusion miR-145-5p is low expressed in gastric cancer epithelial cells, and MEST is high expressed in gastric cancer epithelial cells; miR-145-5p can target down-regulation of MEST, thereby inhibiting the proliferation, metastasis and invasion of gastric cancer cells.