Background: Interleukin-11 receptor subunit alpha (IL-11RA) contributes to multiple biological processes in various tumors. However, the role of IL-11RA in Lung adenocarcinoma (LUAD) is still undetermined. The study aims to explore the role of IL-11RA in LUAD via an integrated bioinformatics analysis. Methods: TIMER, GEPIA, TCGA and HPA databases analysis were used to detect IL-11RA expression. UALCAN database was used to analysis the correlation between IL-11RA expression and clinicopathological parameters of LUAD. Kaplan-Meier Plotter, TCGA and GEO databases were used to analysis overall survival (OS) and progression-free survival (PFS) of the LUAD patients. Univariate Cox regression analysis was used to assess the prognostic value of IL-11RA in different clinical characteristics. GSEA, and TIMER were used to investigate the relationship between IL-11RA and immune infiltration.Results: The expression of IL-11RA was down-regulated in LUAD tissues. Furthermore, IL-11RA expression was closely associated with clinical stage, lymph node stage and smoking habits. The patients with lower IL-11RA expression had poorer overall survival (OS) and progression-free survival (PFS). Lower IL-11RA expression was significantly associated with its hypermethylation, and the hypermethylation of CpG site at cg14609668 and cg21504624 was obviously correlated with poorer OS. Then, we found that IL-11RA may play an important role in LUAD progression and immune regulations. Notably, High expression of IL-11RA may suppress the progression of LUAD through inhibiting cell proliferation and immune cell infiltration, especially in B cells, CD4+ T cells, and Dendritic Cell. Conclusions: Decreased IL-11RA expression correlates with poor prognosis and immune infiltration in LUAD. Our work highlights IL-11RA might be a potential biomarker for prognosis and provide a new therapeutic target for LUAD patients.