Objective: To explore the effect of circ_POLA2 on the proliferation, migration and invasion of gastric cancer cells and the possible mechanism.Methods: QRT-PCR was used to detect the expression of circ_POLA2 and miR-30c-5p in gastric cancer tissues and adjacent tissues.Pearson anal. was used to analyze the correlation between circ_POLA2 and miR-30c-5p expression in gastric cancer tissues.Human gastric cancer cells HGC-27 were cultured in vitro and grouped according to different transfectants: a si-NC group, a si-circ_POLA2 group, a miR-NC group, a miR-30c-5p group, a si-circ_POLA2 + NC-inhibitor group and a si-circ_POLA2 + miR-30c-5p-inhibitor group.CCK-8 method and transwell experiments were resp. used to detect cell proliferation, migration and invasion capabilities.The dual luciferase reporter experiment was used to detect the effect of miR-30c-5p overexpression on wild-type and mutant circ_POLA2 luciferase activity.Western blotting was used to detect the expression of PI3K, p-PI3K, Akt, p-Akt, MMP-2 and MMP-9.Results: Compared with adjacent tissues, the expression of circ_POLA2 in gastric cancer tissues was increased, while the expression of miR-30c-5p was decreased.Circ_POLA2 was neg. correlated with miR-30c-5p.Compared with the si-NC group, the expression of miR-30c-5p in the si-circ_POLA2 group was increased, and cell survival rate, the protein levels of MMP-2 and MMP-9, the ratio of p-PI3K/PI3K and p-Akt/Akt and the number of migrating and invading cells were decreased.Overexpression of miR-30c-5p could inhibit the luciferase activity of wild-type circ_POLA2.Compared with the miR-NC group, the cell survival rate and the protein levels of MMP-2 and MMP-9, the ratio of p-PI3K/PI3K and p-Akt/Akt, and the number of migrating and invading cells in the miR-30c-5p group were decreased.Compared with the si-circ_POLA2 + NC-inhibitor group, the cell survival rate, the protein levels of MMP-2 and MMP-9, the ratio of p-PI3K/PI3K and p-Akt/Akt and the number of migrating and invading cells in the si-circ_POLA2 + miR-30c-5p-inhibitor group were increased.Conclusion: Interfering with circ_POLA2 inhibits the activation of PI3K/Akt pathway by targeting the up-regulation of miR-30c-5p expression, and inhibiting the proliferation, migration and invasion of gastric cancer cells.