[Objective] To investigate the influence of intervertebral distraction height on the clinical results of anterior cervical fusion. [Methods] The data of patients who underwent single level anterior cervical decompression, fusion and internal fixation for cervical spondylosis from 2013 to 2017 were retrospectively analyzed, and the influence of three different intervertebral space extension heights on the clinical results of anterior cervical fusion was analyzed. [Results] A total of 118 patients were included in this study, including 66 males and 52 females, aged 45-73 years, with 24 cases of C4/5, 63 cases of C5/6, 31 cases of C6/7. There were 27 patients in the in situ group (100% - 110% reference height), 57 patients in the moderate distraction group (110% - 130% reference height) and 34 patients in the over distraction group (more than 130% reference height). The postoperative follow-up time was 2-5 years. After 2 years of follow-up, the JOA score of moderate distraction group was higher than that of the other two groups, the difference was statistically significant, vas and NDI scores between groups were not statistically significant, the proximal and adjacent segments of the original end of the hyperextension group were higher than the other two groups, and the difference was statistically significant. The cervical lordosis angle correction of moderate distraction group and over distraction group was better than that of in situ group, and the difference was statistically significant. [Conclusion] Intervertebral distraction height has an impact on the clinical efficacy of anterior cervical fusion. Choosing 110% - 130% of the distraction height can obtain good clinical effect, and has little effect on adjacent segment degeneration.