Objective:To explore the correlation between lactylation-related gene and the treatment, prognosis and tumor microenvironment of gastric cancer.Methods:The gene expression profile and clinical data of gastric cancer and normal tissues in The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets were used to analyze the characteristics of gastric cancer Lactylation-related gene (gLRG). The molecular subtypes of gLRG were identified by consensus cluster analysis. LASSO regression analysis was used to construct gLRG risk score model, and to analyze the differences in immune infiltration in tumor microenvironment and predict prognosis.Single-cell RNA sequencing (ScRNA-seq) data were used to evaluate the expression of key genes in different cells. Finally, immunohistochemistry was used to further explore the expression and prognosis of key gene AADAC in gastric cancer tissues. Statistical analysis was conducted using R4.3.1 and SPSS 27.0 software. Results:Based on the expression levels of gastric cancer Lactylation-related gene, two clusters of lactylation-related molecular subtypes of gastric cancer were identified by consensus cluster analysis. A gLRG risk score model containing 14 key prognostic genes was constructed, and gastric cancer patients were divided into high lactylation score group and low lactylation score group according to the risk score. In the high lactylation score group, patients had short survival time, poor prognosis, and infiltration of M2 macrophages and other immune cells. ScRNA-seq analysis revealed that AADAC was enriched in all cell types.Prognostic analysis of fourteen key genes showed that AADAC was associated with the prognosis of gastric cancer. Immunohistochemistry showed that AADAC was highly expressed in gastric cancer tissues, and was related to pathological stage and differentiation degree. Conclusions:The lactylation-related genes are closely related to the tumor microenvironment of gastric cancer. The model based on gastric cancer Lactylation-related gene has good prognostic prediction performance. Among them, the expression of AADCA is significantly up-regulated in gastric cancer tissues, which is expected to become a prognostic marker and potential therapeutic target of gastric cancer.