Objective To explore the biological functions and specific molecular mechanisms of miR-638 in gastric cancer. Methods The mRNA expressions of miR-638 and MACC1 in gastric cancer cells were detected by QRT-PCR, and the protein expression of MACC1 in gastric cancer cells was detected by Western blot. The dual luciferase experiment verified the targeted binding relationship between MACC1 and miR-638. The CCK8 method was used to determine the cell proliferation activity. The scratch healing test and transwell test were used to evaluate its migration and invasion capabilities. Flow cytometry experiments to detect cell cycle distribution. Results miR-638 is down-regulated in gastric cancer cells. Overexpression of miR-638 inhibits the proliferation, migration and invasion of gastric cancer cells. MACC1 expression is significantly up-regulated in gastric cancer cells, miR-638 targets the inhibition of MACC1 expression. miR-638 inhibits the proliferation, migration and invasion of gastric cancer cells by targeted down-regulation of MACC1. Conclusion miR-638 inhibits the occurrence and development of gastric cancer cells by targeting down-regulation of MACC1.