Objective To explore the clinical effect of occipital-cervical fusion and its impact on cervical curvature, and preliminarily study the causes of postoperative dysphagia. Methods The data of 24 patients who underwent occipito-cervical fusion in the Fourth People’s Hospital of Zigong between January 2014 and December 2018 were retrospectively analyzed, including 13 males and 11 females, aged 33-82 years, with an average age of (58.3±13.3) years. Among them, there were 14 cases of atlas fractures, 6 cases of atlantoaxial fractures, 1 case of intraspinal canal space-occupying lesion, 2 cases of chronic atlantoaxial dislocation with spinal cord compression, and 1 case of instability caused by inflammatory diseases. Japanese Orthopedic Association (JOA) score and Visual Analogue Scale (VAS) score were used to evaluate neurological function and pain of patients preoperatively and postoperatively. Occipito-cervical angle (O-C2) and lower cervical angle (C2-C7) were measured to evaluate the preoperative and postoperative angle changes in patients. The causes of postoperative dysphagia were analyzed. Results All the 24 patients were followed up for 8-50 months (26.3 months on average). The mean JOA score increased from 11.6±1.5 before surgery to 15.4±1.2 at the last follow-up, and the mean VAS score decreased from 6.4±1.1 before surgery to 2.0±0.6 at the last follow-up; the differences between the two time points were statistically significant (P<0.001). The bone graft fusion rate was 95.8% (23/24). The mean O-C2 angle decreased from (16.5±7.6)° before surgery to (14.7±4.5)° at the last follow-up, with no statistical significance (P=0.395). The mean angle of C2-C7 increased from (9.4±5.5)° before surgery to (16.3±3.5)° at the last follow-up, and the difference was statistically significant (P<0.001). Two patients developed postoperative dysphagia, possibly due to fusion in a flexion position. Conclusion Occipito-cervical fusion has reliable efficacy in treating occipito-cervical instability, with a high fusion rate and a low incidence of complications, but it will change the physiological curvature of upper and lower cervical vertebra, and fusion in a flexion position may cause postoperative dysphagia.