BACKGROUND Obesity is an important factor to cause the obstructive sleep apnea-hypopnea syndrome (OSAHS). Higher body mass index (BMI) often results in more severe OSAHS. Currently, the common measures for controlling the weight mainly include diet control, increase exercise and so on. Motivational interviewing (MI) could explore the patient’s internal state and make the patient realize his/her ambivalence, resulting in the change in his/her behavior. This process emphasizes respecting the patient’s autonomy. AIM To evaluate the effect of MI on the weight control of patients with OSAHS. METHODS A randomized controlled study was conducted in 100 obese OSAHS patients undergoing surgical treatment at Shengjing Hospital of China Medical University. The patients were divided into an intervention group and a control group, with 50 cases each. The control group was given routine health education after the operation; in addition to the regular health education, the intervention group was given MI according to a predetermined plan. Obesity-related indicators, postoperative complications, and the sleep status of both groups were evaluated before and 6 mo after the intervention. RESULTS Patients in the intervention group had significantly improved body weight, BMI, and waist and neck circumferences compared with patients in the control group ( P < 0.05). Regarding complications at 6 mo after operation, the incidence of cough and reflux in patients in the intervention group was significantly lower than that in the control group ( P < 0.05). In addition, the Epworth Sleepiness Scale and Self-Rating Scale of Sleep scores of patients in the intervention group were significantly lower than those in the control group, and the sleep status of patients in the intervention group was improved ( P < 0.05). CONCLUSION MI intervention has a significant advantage over postoperative routine health education. It can greatly change the lifestyle, further control the postoperative weight, reduce the occurrence of complications, improve the quality of sleep, and improve long-term postoperative efficacy in OSAHS patients.