Background: Acyl-coenzyme A cholesterol acyltransferase (ACAT) is a membrane-binding enzyme, which localizes in the endoplasmic reticulum. ACAT2 can promote the progression of colon cancer, but its efficacy in lung adenocarcinoma(LUAD) remains uncertain. Method: Analysis of ACAT2 expression was performed using TIMER2.0 database. The GEPIA database was utilized to analyze the correlation between ACAT2 expression and pathological stage of the tumour. The Kaplan-Meier analysis was performed to analyze its potential in clinical prognosis. The correlation between expression of ACAT2 and functional status of different tumours was analyzed in the CancerSEA database and displayed as a heatmap. Molecular interaction network analysis performed with the STRING tool. Results: High ACAT2 expression was associated with a poor DFS and OS in LUAD patients. Cox regression analysis indicated that the poor outcomes might be related to tumour stage, nodal stage, distant metastatic stage. ACAT2 was involved in many biological processes including the cell cycle, DNA repair, DNA damage, and proliferation. Enrichment pathway analysis revealed four ACAT2 related genes, ACOX1, EHHADH, OXCT1, DLAT.