Objective：To identify genes associated with mRNA expression-based stemness index（mRNAsi）in gastric cancer（GC） and explore their functions. Methods：Bioinformatics analysis was conducted using The Cancer Genome Atlas（TCGA）database and microarray GSE66229 dataset. The expression of TCEAL7 in tissues and cell lines was assessed by quantitative real-time polymerase chain reaction（qRT-PCR）and immunohistochemistry. The effect of TCEAL7 overexpression on the proliferation，migration，invasion， and stemness characteristics of GC cells was studied. Results：The expression of TCEAL7 was downregulated in GC. High expression of TCEAL7 was associated with poorer prognosis. Overexpression of TCEAL7 inhibited the proliferation，migration and invasion of GC cells，attenuated spheroid formation，and decreased the population of stem-like CD44^high/CD24^high cells. The nomogram which included clinical features and TCEAL7 expression showed good accuracy and discrimination for predicting the prognosis of patients with GC. Conclusions：TCEAL7 was identified as a mRNAsi - related prognostic factor in GC，inhibiting the malignancy of tumor cells and attenuating stemness characteristics.