Objective To investigate the changes of serum C reactive protein (CRP),D-two polymer (D-D) and calcitonin (PCT) in patients with severe chronic obstructive pulmonary disease ( COPD) and its clinical value. Methods A retrospective analysis was conducted in 146 patients with severe COPD at acute attack in Tongji Huangzhou Hospital of Huazhong University of Science and Technology from December 2015 to December 2017.In addition,146 cases of COPD at remission stage (remission group) and 80 healthy subjects (control group) who were admitted to the hospital during the same period were selected.The serum levels of D -D,hs-CRP and PCT were compared among the three groups.At the same time,the levels of serum D-D,hs-CRP and PCT in patients with no bacterial infection or different pulmonary function classification were compared .Results The serum levels of D-D, hs-CRP and PCT in the acute group [(1 927.4 ±83.4) μg/L,(39.3 ±3.2) mg/L,(5.8 ±1.7) ng/mL] were significantly higher than those in the remission group [(314.2 ±69.2)μg/L,(16.4 ±3.4)mg/L,(1.8 ±0.7)ng/mL], which in the remission group were also significantly higher than the control group [(231.7 ±58.5) μg/L,(3.8 ± 1.5)mg/L,(0.4 ±0.1)ng/mL],the differences were statistically significant (F＝35.487,11.266,6.752,P＝ 0.001,0.005,0.000).The serum levels of hs -CRP and PCT in the acute phase combined with bacterial infection group[(41.4 ±1.7) mg/L,(6.4 ±1.4) ng/mL] were higher than those in the non bacterial infection group [(36.3 ±1.2)mg/L,(5.0 ±1.0)ng/mL](F＝16.541,4.467,P＝0.000,0.011),but there was no statistically significant difference in D -D level ( P ＞0.05).There were statistically significant differences in serum D -D, hs-CRP and PCT levels among patients with different pulmonary function classification [serum D-D:(2 083.5 ± 88.3)μg/L vs.(1 727.3 ±71.3)μg/L vs.(1 523.5 ±67.3)μg/L;hs-CRP:(63.8 ±19.5)mg/L vs.(29.5 ± 10.4)mg/L vs.(10.6 ±3.2) mg/L;PCT:(6.2 ±1.3) ng/mL vs.(3.4 ±0.9) ng/mL vs.(1.3 ±0.4) ng/mL] (F＝34.493,15.488,6.567,P＝0.000,0.001,0.018),and the higher the pulmonary function classification ,the higher the above indicators(all P＜0.05).Conclusion The levels of serum CRP,D-D and PCT in patients with severe COPD at acute attack are significantly increased ,and the increase of the patients with bacterial infection is more obvious,and the index level is positively correlated with the classification of lung function ,which can provide a reference for clinical practice.