Objective: To study the correlation between serum 8-hydroxydeoxyguanylate levels, disease severity, and oxidative stress in patients with obstructive sleep apnea-hypopnea syndrome. Methods: Sixty OSAHS patients - treated at our department of respiratory medicine from July 2018 to July 2019 - were selected for the study group. According to their sleep apnea-hypopnea index (AHI) and minimum blood oxygen saturation (SaO2min), OSAHS patients were divided into three groups: mild group (n=24), moderate group (n = 20), and severe group (n=16). Healthy people were collected in the hospitals' physical examination centre as the control group (n=30). Five millilitres of fasting blood of all the subjects were taken and tested, and the serum 8-hydroxydeoxyguanylate (8-OHdG), brain hemoglobin (NGB), malondialdehyde (MDA), supertrophic disproportion Enzyme (SOD), and glutathione peroxidase (GSH-Px) levels were compared to investigate the relationship between serum 8-OHdG levels, disease severity, and oxidative stress in OSAHS patients. Results: There were significant differences in 8-OHdG, NGB, and MDA levels in each group: the severe group>the moderate group>the mild group >the control group (P<0.05). There were also significant differences in SOD and GSH-Px levels: the severe group 8-OHdG was directly proportional to AH1 and NGB (r=5.112, 3.251, 2.436, P<0.05), and inversely proportional to SaO2min (r=5 .243 , P<0.05). 8-OHdG was negatively correlated to SOD and GSH-Px (r=-6221, -5.489, P<0.05), and was positively correlated to MDA (r=3.251, P <0.05). Conclusion: The level of serum 8-OHdG in OSAHS patients is higher than that in healthy people, and it is positively correlated to the disease severity and oxidative stress.