Objective To analyze the risk factors of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea hypopnea syndrome (OSAHS) by observing the clinical characteristics of patients with COPD-OSAHS overlap syndrome (OS). Methods A total of 123 COPD patients from October 2018 to December 2019 were selected in the Department of Respiratory Diseases of Yan′an University Affiliated Hospital. They were divided into COPD group (n=64) and OS group (n=59). SPSS statistics 22.0 was used for data analysis. According to different data type, t test or χ²test was used for data comparison between two groups. Pearson correlation coefficient and multivariate logistic regression were used to analyze factors of OSAHS in the COPD patients. Results The apnea hypopnea index (AHI) of the OS group was correlated positively with neck circumference, body mass index (BMI), arterial partial pressure of carbon dioxide (PaCO₂) (r=0.774,0.905,0.761, P<0.05) and negatively with forced expiratory volume in the first second to forced vital capacity(FEV₁/FVC), arterial partial pressure of oxygen(PaO₂) (r=-0.597, -0.856, P<0.05). Neck circumference (OR=3.453,95%CI 2.004-5.948; P=0.000), BMI (OR=3.467,95%CI 2.268-6.696; P=0.000), snoring (OR=5.925,95%CI 2.622-13.386; P=0.000), and smoking (OR=2.503,95%CI 1.076-5.822; P=0.033) were independent risk factors of COPD-OSAHS overlap syndrome. Conclusion Increased neck circumference and BMI, smoking, and snoring are risk factors of COPD-OSAHS overlap syndrome, and patients with overlap syndrome are more likely to have hypoxia and hypercapnia than COPD patients.