Objective：This study aimgs to investigate the expression of plasma exosomal miR-1260b in patients with lung adenocarcinoma and its correlation with clinical features. Methods：Exosomes were extracted from the plasma of the patients with lung adenocarcinoma. The size and distribution of exosomes were identified by transmission electron microscopy（TEM），nanoparticle tracking analysis（NTA） and Western blot. qRT-PCR was used to detect the expression of exosomal miR-1260b. Results：Exosomes wre widely present in the plasma of patients with lung adenocarcinoma. Subgroup analysis found that plasma exosomal miR-1260b was highly expressed in> 3 cm compared with ≤ 3 cm group（P=0.010）；Compared with the N0 group，plasma exosomal miR-1260b was increased in the N1（P＜0.05）and N2（P＜0.001）groups；Compared with the spread without air spaces group，plasma exosomal miR-1260b was elevated in the spread through air spaces group（P＜0.001）. Compared with the non-relapse/metastasis group，plasma exosomal miR-1260b was highly expressed in the relapse/metastasis group（P=0.038）. Conclusion：Plasma exosomal miR-1260b is highly expressed in patients with lung adenocarcinoma，and is related to tumor size，stas and recurrence/metastasis. It can be used as a molecular target for the diagnosis and treatment of lung adenocarcinoma patients.