Objective To explore the correlation between Hemoglobin levels and severity of chronic obstructive pulmonary disease patients. Methods 300 cases of patients with chronic obstructive pulmonary disease (COPD) diagnosed in our hospital between From October 2014 to October 2016 were chosen. Subjects were categorized as anemic, polycythemic and normocythemic. The BODE score [FEV1%, modified medical research council scale(mMRC score), 6 minutes walking distance(6MWD)] were compared among three group, and the correlation analysis and the proportion of different severity different severity (Light to medium/heavy to extreme serious) were carried with Pearson method. Results The age, the proportions of the coronary heart disease, diabetes, mMRC score in polycythemic or normocythemic the proportion of Light to medium/heavy to extreme serious were significantly lower than those in anemic(P<0.05). But the FEV1%/FEV1/FVC% and 6MWD were significantly higher than those in anemic,(P<0.05). Conclusion Analysis results showed that the hemoglobin level were negative with the BODE index and FEV1 %, but postitive with mMRC score. Conclusion The hemoglobin levels are closely associated with the severity of disease in COPD patients, Anemia in COPD was a risk factor for poorer exercise capacity and quality of life, and these outcomes were linearly associated with hemoglobin. High hemoglobin level had less effects on degree of disease in patients with COPD.