Lung cancer, characterized by its high incidence and mortality rates, is a challenging malignancy to treat. Immunotherapy has emerged as a crucial treatment modality, yet its effectiveness varies significantly among patients due to the diverse immune microenvironment involved. Our study aims to analyze the similarities and differences in immune cell profiles across different subtypes of lung cancer. We employed a comprehensive two-sample Mendelian randomization analysis to establish causal connections between immune cells and lung cancer. We examined differential expression of 731 immune cell types and compared their profiles among various lung cancer subtypes. Our analysis revealed that 47 immune cell types exhibited differential expression in lung cancer, with 15 showing a protective effect and 32 having a tumor-promoting effect. Notably, we observed greater similarities in immune cell profile between squamous carcinoma and adenocarcinoma subtypes, while small cell lung cancerHHHH displayed less overlap with the other two types. Specifically, CD4+ naive T cells showed differential expression across all three lung cancer subtypes, whereas three other immune cell types exhibited differential expression exclusively in adenocarcinoma and squamous cell carcinoma. Our findings substantiate a causal link between immune cell dynamics and lung cancer progression. Moreover, our identification of distinct immune cell composition among histological subtypes of lung cancer may serve as a valuable reference for further investigation into immunotherapeutic strategies.