Objective To explore the value of percentage of forced expiratory volume in the predicted value in the first second (FEV₁%pred) combined with sleep apnea clinical score (SACS) in primary screening for patients with chronic obstructive pulmonary disease (COPD) complicated with obstructive sleep apnea (OSA). Methods A total of 299 patients diagnosed with COPD in our department from January to December 2020 were selected as the research objects. All patients completed FEV₁%pred examination of pulmonary function and SACS evaluation, and were monitored by overnight polysomnography (PSG). According to their sleep apnea hypopnea index (AHI), the patients were divided into simple COPD group and COPD combined with OSA (overlap syndrome, OVS). SPSS statistics 23.0 was used for statistical analysis. According to the data types, independent sample t-test or Chi-square test was adopted for intergroup comparison. Pearson′s correlation coefficient was used to analyze the correlation in FEV₁%pred, SACS and AHI. Receiver operating characteristic (ROC) curve was employed to analyze the value of FEV₁%pred combined with SACS in prediction of OVS in COPD patients. Results FEV₁%pred [(53.4±15.1) vs (43.6±13.9)%, P<0.05] and SACS [(19.1±3.9) vs (7.3±2.1) points, P<0.05] were significantly higher in the OVS group than the COPD group. Correlation analysis showed that AHI was positively correlated with FEV₁%pred (r=0.631, P<0.05) and SACS (r=0.689, P<0.05). ROC curve suggested that the best cut-off value of FEV₁%pred in the diagnosis of OVS was 48.3%, and the sensitivity and specificity were 81.3% and 75.4%, respectively. The best cut-off value of SACS for the diagnosis of OVS was 16, and the sensitivity and specificity were 83.2% and 79.3%, respectively. Taking FEV₁%pred ≥48.3% and SACS ≥16 points as joint indicators, the area under the curve for the diagnosis of OVS was 0.812 (95%CI 0.781-0.903), and the sensitivity and specificity were 85.2% and 79.5%, respectively. Conclusion FEV₁%pred combined with SACS has good predictive value in the screening of OVS in COPD patients.