Lung cancer is the most common cancer type and major cause of death from malignancy worldwide. Immune cells such as lymphocytes infiltrated in tumor are identified as strong prognostic biomarkers for lung adenocarcinoma (LURD) patients. In our research, based on immune cell signatures infiltrated in tumor immune microenvironment, we developed and verified a risk score model by selecting six valuable prognostic genes: CD1C, CR2, MS4A1, SFTPC, STAP1 and TFF1 for risk stratification and survival prediction in LURD patients. Furthermore, the associations of risk score with tumor-infiltrating immune cells, immunotherapy-related biomarkers and immune checkpoints were also evaluated. Based on above, we made conclusions that the risk score model as a robust prognosis biomarker can screen the population who can benefit potentiallyfrom immunotherapy, thus improving diagnostic accuracy and optimizing clinical decision in LURD management.