〔Abstract〕 Objective To explore the effect of ATP-binding cassette transporter subfamily G2(ABCG2) gene on human gastric cancer cells and explore its possible mechanism. Methods 84 pathological specimens that are positive for epidermal growth factor 2(HER2) were collected. ABCG2 protein expression was detected by immunohistochemistry, and their clinicopathological characteristics was analyzed. Lentivirus was transfected into HER2-positive gastric cancer cell lines NCI-N87 and MKN-7 to construct a stable cell line model; RT-PCR, Western blot and immunofluorescence were used to detect transfection efficiency and ABCG2 expression; Scratch experiment was used to observe the influence of ABCG2 on cell migration; Western blot was used to detect the protein expression of HER2, PI3 K/Akt signaling pathway. Results Among 84 pathological specimens, 60 cases were ABCG2 positive(71.4%) while 24 cases were negative(28.6%). The double positive of HER2 and ABCG2 was closely related to the differentiation degree of gastric cancer and the later treatment; compared with the Cell group and the LV5 NC group, the mRNA and protein expression levels of ABCG2 in the LV5-homo group increased(P<0.01). Compared with the Cell group and the LV5 NC group, the expression levels of HER2, PI3 K and Akt phosphorylation(P-Akt) in the signaling pathway of the LV5-homo group increased(P<0.05). Compared with the Cell group and the LV5 NC group, the expression of ABCG2 in the LV5-homo group increased and promoted the migration of gastric cancer cells(P<0.05). Conclusion ABCG2 is widely expressed in HER2-positive gastric cancer cells and is closely related to the metastasis, differentiation and TNM staging of gastric cancer; ABCG2 up-regulates the HER2-PI3 K/Akt pathway, promotes the migration of gastric cancer cells, and affects the expression of key proteins in the pathway, which provides a new idea for the study of drug resistance mechanisms in gastric cancer.