Abstract： Objective:To evaluate the expression level of miR-191 in peripheral blood extracellular vesicles in the diagnosis of early non-small cell lung cancer (NSCLC).Methods:There were 60 early NSCLC patients admitted from January to December 2018 in the second hospital of Yulin city selected as the observation group and 60 healthy patients who underwent physical examination at the same time selected as the control group.The peripheral blood extracellular vesicles of two groups of patients were collected.To compare the expression level of miR-191 peripheral blood free and in peripheral blood extracellular vesicles of two groups patients.The plasma cells were analyzed using the subjects′ working characteristic curves.The diagnostic efficacy of the expression level of miR-191 in plasma extracellular vesicles in early NSCLC was analyzed by using the working characteristic curve of the subjects, and the correlation between the expression level of miR-191 in peripheral blood extracellular vesicles and the clinicopathology was analyzed.Results:The transmission electron microscope analysis showed that the extracellular vesicles in the peripheral blood of patients with early NSCLC were rich in content, complete in shape, and varied in size.The nanoparticle stracking analysis showed that the maximum peak value of nanoparticles was (167.6±10.3) nm, and the diameter of most particles was less than 200 nm.The level of extracellular vesicle miR-191 in the observation group was significantly higher than that in the control group ( t=15.686, P<0.001). The analysis results of the working characteristic curve of the subjects showed that the area under the curve of early NSCLC was predicted to be 83.6% ( P<0.05), which was significantly higher than that of oncoembryonic antigen (50.1%), squamous cell carcinoma antigen (62.1%), keratin 19 fragment (60.0%) and three combinations (71.5%). The expression level of miR-191 in extracellular vesicles in peripheral blood of patients with early NSCLC was related to TNM stage ( t=3.126, P<0.05). Conclusions:The expression level of miR-191 in peripheral blood extracellular vesicles of patients with early NSCLC is significantly increased, which can be used as one of the potential markers in the clinical detection of early non-small cell lung cancer and has important clinical significance.