Objective To assess miR-219a-5p expression and its promoter methylation level in gastric cancer and adjacent tissues, and to explore its effect on the biological functions of gastric cancer cell lines. Methods The expression and methylation level of miR-219a-5p in gastric cancer and adjacent tissues were detected by qPCR and MSP. Proliferation and apoptosis of gastric cancer cells were detected by Cell Counting Kit-8 assays and flow cytometry after overexpression of miR-219a-5p. Results MiR-219a-5p expression was generally downregulated in gastric cancer tissues. The relative expression of miR-219a-5p in cancer tissues (0. 769 ± 0. 95) was significantly lower than that in adjacent tissues (2. 114 ± 5. 10) (P<0.05). The DNA methylation level in the miR-219a-5p-downregulated group was significantly higher than that in the miR-219a-5p-upregulated group. Proliferation and invasion of MGC-803 cells overexpressing miR-219a-5p were inhibited significantly ( P< 0.05), apoptosis in the overexpression group was increased significantly ( P< 0.05), and expression of apoptosis-related protein caspase-3 was significantly higher ( P< 0.05). Conclusions MiR-219a-5p is generally underexpressed by methylation in gastric cancer tissue, and inhibits cell proliferation and migration, promotes apoptosis, and play a role similar to tumor suppressor genes. It is expected to become a new target for diagnosis and treatment of gastric cancer.