【Abstract】 Objective The present study aimed to investigate the association between serotonin (Serotonin, 5HT) and chronic obstructive pulmonary disease（COPD）. Methods 44 patients with COPD in our hospital from January 2015 to December 2016 were selected as observation group. 23 healthy people were chosen as control group. 5HT and Creactive protein (CRP) expression level and other clinic indexes, including FEV1, FVC, FEV1/FVC%, FEV1% were observed. Results The levels of serum 5HT were significantly elevated in COPD patients compared with controls (P=0.00). The levels of CRP were also significantly increased in COPD patients (P=0.00). Regression correlation analyses showed that both 5HT and CRP levels were not correlated with lung function (r=0.39, P=0.80 for 5HT; r=0.13, P=0.196 for CRP), while 5HT levels were positively correlated with CRP (r=0.47, P =0.001) in the COPD group. ConclusionThe present study shown that 5HT may play a role in COPD, especially in system inflammation of COPD.