This work is aimed at exploring the clinical efficacy of continuous positive airway pressure (CPAP) in treatment of patients with arrhythmias combined with obstructive sleep apnea (OSA). Through evaluating serum native thiol, malonaldehyde (MDA) and nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) in these patients and describing the effects on oxidative parameters of CPAP therapy for 3 months, we confirmed the impact of oxidative stress on arrhythmias. A total of 64 patients with OSA combined with arrhythmias were collected from April 2014 to April 2017 with full clinical information. Patients were divided into two groups (paired experiment design): 32 patients in group A (control group), who received unchanged anti-arrhythmia treatment and 32 patients in group B, who were subjected to unchanged pharmacological anti-arrhythmia therapy combined with CPAP. OSA related parameters were compared between the two groups after 3-month therapy. And the levels of parameters of oxidative stress in patients were measured before and after CPAP therapy. After 3 months of CPAP therapy, compared with the control group, the percentage of sage N3 (NREM 3) and stage R (REM) in total sleep time was significantly increased, while apnea-hypopnea index (AHI) and the Epworth Sleepiness Scale (ESS) score were evidently decreased. Meanwhile, the lowest oxygen saturation (LSpO(2)) was also elevated after CPAP treatment for 3 months. The CPAP therapy significantly prevented the occurrence of arrhythmias (P<0.05). Both the MDA level and NADPH oxidase levels were significantly lower in the group B than in the group A (P<0.05). But serum native thiol was improved by CPAP treatment (P<0.05). In conclusion, proper use of CPAP therapy provides significant benefits for the treatment of arrhythmia in patients with OSA.