Abstract: Objective To investigate the effect of microRNA-148a-3p（miR-148a-3p）on invasion， migration and expression of muscle RAS oncogene homolog（MRAS） in gastric cancer HGC-27 cells. Methods The cryopreserved gastric cancer cell line HGC-27 was recovered and cultured to the logarithmic growth phase. The miR-148a-3p analog and its negative control （miR-NC）were transfected into HGC-27 cells （miR-148a-3p transfection group and miR-NC group）， and HGC-27 cells without transfection were chosen as blank control（untransfection group）. The level of miR-148a-3p was detected by real-time quantitative PCR（QPCR） at 48 h after transfection. Transwell and scratch test were used to compare the number of penetrating-membrane cells and relative migration distance at 48 h after transfection in each group to evaluate the migration and invasion ability. The mRNA and protein levels of MRAS in each group at 48 h after transfection were detected by QPCR and Western blotting， respectively. Double luciferase reporter gene test was employed to verify the targeting regulation between miR-148a-3p and MRAS. Results QPCR detection showed that miR-148a-3p level of miR-148a-3p transfection group was 2.612±0.213，higher than 0.954±0.098 of untransfected group and 0.983±0.196 of miR-NC group，and the difference was statistically significant （P<0.05）. Scratch results show that the relative migration distance of miR-148a-3p group was 0.615±0.019， lower than 1.021±0.019 of untransfection group and 0.948±0.022 of miR-NC group （P<0.05）. Transwell assay showed that the transmembrane cell number in miR-148a-3p transfected group was 83±17， less than 124±17 of untransfection group and 136±26 of miR-NC group （P<0.05）. QPCR and Western blotting results showed that mRNA and protein levels of MRAS in miR-148a-3p transfection group were 0.614±0.057 and 0.553±0.049， lower than 1.106±0.024 and 0.824±0.091 of untransfected group and 1.095±0.031 and 0.784±0.121 of miR-NC group （P<0.05）. MiR-148a-3p significantly decreased the luciferase activity of wild-type MRAS-3’untranslated region plasmid transfected cells， but had no significant inhibitory effect on the luciferase activity of mutant MRAS plasmid transfected cells.Conclusion MiR-148a-3p may inhibit the invasion and migration of gastric cancer HGC-27 cells by targeting MRAS.