Pulmonary function testing, regarded as the "gold standard" for the classification and evaluation of therapeutic efficacy in chronic obstructive pulmonary disease (COPD), is a core method for its diagnosis and management. Among these tests, pulmonary ventilation parameters can effectively reflect the degree of airway obstruction; however, they are limited in detecting early lung parenchymal damage and microvascular lesions. In contrast, the diffusing capacity of the lung for carbon monoxide (DLCO) is an important indicator of pulmonary gas exchange function, which responds sensitively in the early stages of COPD and provides valuable clues for early disease detection. This article systematically discussed the role of DLCO in the early identification of COPD, assessment of disease severity, risk of acute exacerbations, long-term prognosis, and summarized its unique clinical value in COPD and related comorbidities. DLCO might serve as an alternative indicator for disease evaluation or prognostic assessment in patients with poor lung function or advanced age who were unable to complete pulmonary ventilation testing. Furthermore, in patients with COPD complicated by pulmonary hypertension, heart failure, or lung cancer, DLCO could effectively reflect the severity of comorbidities and assist in prognostic evaluation. This review provided a useful reference for future studies on DLCO in patients with COPD and its comorbid conditions.

肺功能检查作为慢性阻塞性肺疾病（COPD）分级和疗效评估的"金标准"，是COPD诊断与管理的核心手段，其中，肺通气功能指标能有效反映气道阻塞程度，但难以早期识别肺实质损伤及微血管病变。相比之下，肺一氧化碳弥散量（DLCO）是评估肺气体交换功能的重要指标，在COPD早期即可迅速反应，为疾病早期识别提供重要线索。本文系统探讨DLCO对COPD患者在疾病早期识别、病情严重程度、急性加重风险及远期预后的作用，总结DLCO在COPD及其合并症评估中的独特价值。本文表明，临床中对于肺功能差、年龄大等因素无法完成肺通气功能检查的患者，可选择DLCO作为病情评估或预后的一种替代指标。针对COPD合并肺动脉高压、心力衰竭和肺癌患者，DLCO可有效识别合并症严重程度或预后判断，本文为COPD及其合并症患者的DLCO研究提供一定参考。