This study investigates the impact of complications associated with chronic obstructive pulmonary disease (COPD) on pulmonary function and inpatient medical expenditures in the Zhongshan region. A retrospective analysis of data from January 2012 to December 2021 was conducted, focusing on lung function and hospitalization expenses for COPD patients (n = 272). The included cases were initially categorized into a simple group (without comorbidities, n = 99) and a nonsimple group (with comorbidities, n = 173). Changes in lung function within each subgroup over a decade were evaluated, along with the average annual hospitalization rate, average duration of hospital stay, and mean hospitalization cost for COPD patients. A comparison between the simple group and the nonsimple group of COPD patient's uncovered statistically significant distinctions (P < .05) in age, extent of lung function alteration, average annual hospitalization frequency, and average hospitalization cost. Moreover, multivariable logistic regression analysis showed that, after adjusted for age, sex, smoking, and hospitalizations, patients with comorbidities (nonsimple group) were independently associated with lung function changes (beta = 4.048, 95% CI: 1.435-6.659, P = .003) compared to those without comorbidities (simple group). Comorbidities have a substantial impact on the lung function of COPD patients. Furthermore, they are associated with increased hospitalization frequency, elevated hospitalization costs, and a higher economic burden of hospitalization for COPD patients.