Abstract: Objective To screen the microRNA（miRNA） associated with metastasis of gastric cancer and understand the differential expression as well as the biological analysis of miR-218. Methods The differential expression of miRNA in gastric cancer cell lines with low metastatic potential（SGC7901-NM and MKN28-NM） and high metastatic potential（SGC7901-M and MKN28-M） were detected by real-time fluorescence PCR（qPCR） and miRNA microarray. The total RNA was extracted in 10 cases of gastric cancer tissues and corresponding metastatic lymph nodes as well as the gastric cancer cell lines with different metastatic potential. The expression of miR-218 was detected in different cells and tissues by qPCR. Results Microarray detection of gastric cancer cell lines with different metastatic potential found that compared with SGC7901-NM cells， 47 miRNAs were down-regulated and 15 miRNAs were up-regulated in SGC7901-M cells. Moreover， compared with MKN28-NM cells， 41 miRNAs were down-regulated and 83 miRNAs were up-regulated in MKN28-M cells. Totally， 34 miRNAs were down-regulated and 11 miRNAs were up-regulated in SGC7901-M and MKN28-M cells. As for gastric cancer cell lines with different metastatic potential and normal human immortalized gastric epithelial cell line GES， the miR-218 expression was lower in 4 gastric cancer cell lines with different metastatic potential than that in GES， and the difference was statistically significant（P＜0.05）. The expression of miR-218 in gastric cancer cell lines with high metastatic potential was significantly lower than that of low metastatic potential， and the difference was statistically significant（P＜0.05）. The expression level of miR-218 in gastric cancer lymph node metastasis was 0.23±0.02， which was significantly lower than 1.09±0.05 of primary gastric cancer， and the difference was statistically significant（P＜0.05）. Conclusion The expression of miRNA in gastric cancer is different， and there is a certain relationship between the upregulation of miR-218 expression and metastasis of gastric cancer.