Objective To evaluate the mental health status of patients with adolescent idiopathic scoliosis (AIS) after bracing treatment, and to observe the severity of depressive symptoms and analyze the influencing factors. Methods We collected the general data and imaging data of AIS patients who underwent bracing treatment in the outpatient clinic of Changzheng Hospital of Naval Medical University (Second Military Medical University) from Jan. 2013 to Jan. 2015. The data included age, gender, body mass index, coronal main curve Cobb angle at the initial treatment and the last follow-up, and duration of bracing treatment. The Center for Epidemiological Studies depression scale for children (CES-DC) and the strengths and difficulties questionnaire (SDQ) were used to assess the severity of depression and the mental health status before bracing treatment and at the last follow-up. Multivariate linear regression model was used to analyze the factors influencing the severity of depression during the bracing treatment. Results A total of 112 patients (16 males and 96 females) were enrolled in our study. We found that the CES-DC score was significantly higher at the last follow-up than that at the beginning (38.4±3.0 vs 26.1±4.2); the scores of the emotional problems (7.7±1.5 vs 5.3±2.2) and peer problems (7.6±1.4 vs 5.0±1.6) in the SDQ were significantly increased and the score of the prosocial behavior was significantly decreased (2.7±0.5 vs 4.2±0.3) at the last follow-up (t=25.22, -27.22, 9.54 and 12.94; all P<0.01). Multivariate linear regression analysis suggested that the depression severity of AIS patients was positively correlated with the pre-treatment coronal main curve Cobb angle, duration of bracing treatment, and pre-treatment SDQ emotional symptom and peer problem scores (all P<0.05), but were negatively correlated with the score of the prosocial behavioral subscale of SDQ. Conclusion The mental health status of patients with AIS is changed after bracing treatment, with increased severity of depression. Active psychological intervention shall be given to patients with large pre-treatment coronal main curve Cobb angle, longer treatment time of bracing, and higher pre-treatment SDQ's emotional symptom scores and peer problem scores, which may improve the post-treatment quality of life of patients.