Objective: To study the proportion of cervical spine instability in treatment-naive rheumatoid arthritis (RA) patients, to investigate the associated neck symptoms, and to analyze the clinical characteristics in treatment-naive RA patients and treated RA patients. Methods: RA patients who underwent cervical spine X-ray imaging from the Department of Rheumatology and Immunology of Peking University Third Hospital and Peking University Shenzhen Hospital from August 2015 to October 2019 and had clinical records of medication administration were included. Clinical and laboratory data including cervical symptoms and X-ray imaging data of cervical spine were collected. The constituent ratio of cervical spine instability in treatment-naive RA patients was statistically analyzed. The clinical data and laboratory data were analyzed by t-test, u-test and chi square to explore the clinical characteristics of the treatment-naive RA patients with cervical instability. Results: Of the 408 RA patients, 105 patients were treatment-naive. Of the 105 treatment-naive patients, 82.9% (87/105) were female, with an average age of (52±14) years, the median duration of the disease was 24 months, the shortest history was 2 weeks, and the longest history was 30 years. 28.6% (30/105) of the treatment-naive RA patients showed cervical spine instability. The prevalence of cervical instability was 13.6% in the treatment-naive RA patients with disease duration less than 24 months. Among them, there were no significant differences in neck symptoms between cervical spine instability group and none cervical spine instability group. The patients with cervical spine instability had a longer duration of disease [60 (18,180) months vs.16 (8,51) months], a higher proportion of peripheral joint deformity (63.3%vs.21.3%), and a lower hemoglobin [(106.90±21.61) g/L vs. (115.77±14.69) g/L]. There was no significant difference in the occurrence of cervical instability in the treatment-naive RA patients compared with treated RA patients. Among the RA patients with cervical instability, there was no statistically significant difference in the composition of each type between the patients with treatment-naive RA and patients with treated RA, except for a shorter duration of disease [120.0 (72.0, 240.0) months vs. 60.0 (27.0, 167.5) months]. Conclusion: 28.6% of treatment-naive RA patients showed cervical spine instability. Cervical instability was also common in RA patients with a duration less than 24 months. There was no significant correlation between cervical instability and neck symptoms. Patients with cervical spine instability had a long-term disease, a higher proportion of peripheral joint deformity and a lower hemoglobin. Controlling the condition of RA early may help to control the progression of cervical involvement in patients with RA.