Purpose <p>Surgical intervention is the preferred approach to prevent further progression of deformity for patients with adolescent idiopathic scoliosis (AIS); among existing surgeries, posterior spinal fusion is predominant. The minimal clinically important difference (MCID) of the total score of the Scoliosis Research Society (SRS)-22r questionnaire is an increase of ≥ 0.4 in surgically treated patients. However, to the best of our knowledge, there is no research exploring the factors influencing SRS-22r total scores exceeding MCID at 2 years postoperatively.</p> Methods <p>Patients who underwent posterior spinal fusion between February 2019 and November 2023 and had a minimum follow-up duration of &gt; 2 years were included. The radiological data and SRS-22r scores were assessed preoperatively and postoperatively. Based on the SRS-22r total scores, the patients were divided into two groups: ‘I’ = Improvement group (∆ Score ≥ 0.4) and ‘NI’ = Non-improvement group (∆ Score &lt; 0.4). Demographic characteristics, radiographic data, and SRS-22r scores were analyzed using chi-square tests and t-tests for comparison. Multivariate logistic regression analysis was used to determine influencing factors.</p> Results <p>A total of 66 patients with AIS underwent posterior spinal fusion surgery were included in the study. The major Cobb angle decreased from 52.9 ± 12.3° preoperatively to 12.3 ± 8.6° (<i>p</i> &lt; 0.001) at 2 years postoperatively, while the SRS-22r total score improved from 3.9 ± 0.4 to 4.2 ± 0.5 (<i>p</i> &lt; 0.001). Overall, 32 of 66 of patients (48.5%) achieved MCID. Preoperatively, the Improvement group trended toward a larger Cobb angle (<i>p</i> = 0.042). Postoperatively, patients who achieved a greater Cobb angle correction in degrees were more likely to attain the MCID (<i>p</i> = 0.003).</p> Conclusion <p>Postoperative MCID attainment in patients with AIS is influenced by both the preoperative Cobb angle and the degree of its surgical correction.</p>