Objective To investigate the expression characteristics and clinical diagnostic value of programmed death receptor 1 （PD-1） and its corresponding ligand （PD-L1） in patients with acute exacerbation of chronic obstructive pulmonary disease （AECOPD）. Methods One hundred and sixty COPD patients who visited Dongzhimen Hospital of Beijing University of Chinese Medicine from April 2024 to November 2024 were included and divided into an acute exacerbation group of 100 cases and a stable group of 60 cases according to the severity of the disease. Additionally， 40 healthy volunteers during the same period were recruited as the control group. The general clinical data of the patients were collected. Chronic Obstructive Pulmonary Disease Assessment Test （CAT） and Modified Medical Research Council Dyspnea Questionnaire （mMRC） Scale were used to test the severity of the disease； respiratory function testing was performed and fasting venous blood was collected for serum PD-1 and PD-L1 testing. Pearson correlation was used to analyze the correlation between serum PD-1， PD-L1， CAT， and mMRC， and multiple logistic regression analysis to identify the influencing factors of AECOPD. Receiver operating characteristic （ROC） curve was drawn to evaluate the diagnostic value of serum PD-1 and PD-L1 level for AECOPD. Results Serum PD-1 level in the stable COPD group and AECOPD group was significantly increased compared with that in the control group， while serum PD-L1 level was significantly decreased， showing statistical significance （P < 0.05）； The level of PD-1 gradually increased with the grading of lung function and the deterioration of AECOPD， with statistical significance （P < 0.05）； Pearson correlation showed that serum PD-1 level was positively correlated with CAT scores in COPD patients， while negatively with CAT scores， showing statistical significance （P < 0.05）； Multiple logistic regression analysis showed that elevated levels of serum interleukin-6 （IL-6）， neutrophil to lymphocyte ratio （NLR）， and PD-1 were risk factors for AECOPD， while elevated level of PD-L1 was protective factor for AECOPD （P < 0.05）； ROC curve showed that the levels of PD-1， PD-L1， IL-6， NLR， and the area under the ROC curve （AUC） for their combined prediction of AECOPD diagnosis were 0.884， 0.867， 0.868， 0.802， and 0.995， respectively. Conclusion Serum PD-1 and PD-L1 in AECOPD patients have presented certain expression characteristics， with elevated PD-1 level while decreased PD-L1 level. Both have good clinical diagnostic value for AECOPD.