Backgrounds: To investigate the inhibiting effects of multi-target anti-microRNA antisense oligonucleotide (MTg-AMOs) on proliferation and migration of human gastric cancer cells. Methods: Single anti-microRNA antisense oligonucleotides (AMOs) and MTg-AMOs for miR-221, 21, and 106a were designed and transfected into SGC7901, a gastric cancer cell line, to target the activity of these miRNAs. Their expression was analyzed using stem-loop RT-PCR and effects of MTg-AMOs on human gastric cancer cells were determined using the following two assay methods: CCK8 for cell proliferation and transwells for migration. Results: In the CCK-8 cell proliferation assay, $0.6{mu}mol/L$ was selected as the preferred concentration of MTg-AMOs and incubation time was 72 hours. Under these experimental conditions, MTg-AMOs demonstrated better suppression of the expression of miR-221, miR-106a, miR-21 in gastric cancer cells than that of single AMOs (P = 0.014, 0.024; 0.038, respectively). Migration activity was also clearly decreased as compared to those in randomized and blank control groups ($28{pm}4$ Vs $54{pm}3$, P <0.01; $28{pm}4$ Vs $59{pm}4$, P < 0.01). Conclusions: MTg-AMOs can specifically inhibit the expression of multiple miRNAs, and effectively antagonize proliferation and migration of gastric cancer cells promoted by oncomirs.