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Background Gastric cancer remains the leading cause of cancer-related death worldwide, with large regional differences in incidence, especially in East Asia. Previous studies have shown that there are differences in the gene expression profiles of gastric cancer tissues in patients from different countries which may be due to genetic, dietary, and lifestyle factors. This study aims to further investigate these differences by analyzing large RNA sequencing data of gastric cancer and adjacent normal tissues from Chinese and Korean patients.Methods The data was downloaded from Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified using R software, and significant expression changes were defined as |log2(fold change)| > 1 and p < 0.01. Genes with expression changes of 10-fold, 100-fold, and 1000-fold were also analyzed. Then, pathway annotation of DEGs was performed using Gene Ontology (GO) and KEGG analysis using the DAVID database.Results The results of the analysis showed that in gastric cancer tissues, the expression levels of a large number of genes changed by more than 2 times, and the changes were mainly up-regulated. Although China and South Korea are both East Asian countries, there are still great differences in gene expression in the tissues of patients in the two countries. This study found that a group of genes changed by more than 1,000 times, and their related biological processes and signaling pathways were largely consistent in the cases of the two countries.Conclusions This study discovered a group of genes whose expression levels in gastric cancer tissues changed by more than 1,000 times compared with normal tissues. These genes, their expression products and related metabolic pathways may become new targets for gastric cancer treatment.