【Abstract】 Objective To investigate the relationship between the level of plasma omentin 1 and the severity of COPD. Methods From August 2017 to July 2018, 124 middle-aged and elderly patients with COPD were selected from respiratory department of Fuling Central Hospital of Chongqing. According to the course of disease, they were divided into acute exacerbation (64 cases) and stable period group (60 cases). Another 60 healthy adults were selected as the control group. The risk assessment of acute exacerbation in stable COPD patients was divided into group A, group B, group C and group D. According to the severity of the disease, acute exacerbation was divided into no respiratory failure (Level 1), acute respiratory failure (Level 2), and acute respiratory failure (Level 3). The levels of plasma reticulin-1 were measured. Results The level of plasma reticulin-1 in the acute exacerbation and stable phase group was significantly lower than that in the control group (P＜0.05). Compared with the stable group, the level of plasma reticulin-1 in the acute exacerbation group was lower (P＜0.01). There was significant difference between group B and group C, between group C and group D in the risk assessment of acute exacerbation of COPD in stable stage (P＜0.05). The more serious the symptoms were, the lower the level of omentin 1 was. In acute exacerbation, the levels of plasma reticulin-1 in three grades decreased in turn, and there was significant difference between the two groups (P＜0.05). There was a significant negative correlation between the severity of acute exacerbation and the level of plasma reticulin-1 (r=-0.525). Conclusion Plasma reticulin-1 may be a biomarker to predict the severity of COPD.