Abstract Objective Explore the effectiveness of diaphragmatic ultrasound combined with rapid shallow breathing index (RSBI) in predicting weaning success from mechanical ventilation in neurocritical patients. Methods This retrospective study analyzed the clinical data of 145 patients who underwent mechanical ventilation for more than 48 hours and were weaned according to weaning criteria. The patients were divided into two groups based on their respiratory status 48 hours post-weaning: a successful weaning group (n=89) and a failed weaning group (n=56). Respiratory mechanics monitoring indices, RSBI, DE and DTF were collected after a spontaneous breathing trial. The value of these indices in predicting weaning success was analyzed using receiver operating characteristic (ROC) curves.Results The RSBI in the failed weaning group was 91.00 (84.75, 102.25), significantly higher than that in the successful weaning group, which was 79.00 (63.00, 90.00). The DE in the failed weaning group was 10.91 (7.88, 14.45), significantly lower than that in the successful weaning group, which was 15.91 (11.86, 19.24). Similarly, the DTF in the failed weaning group was 15.79 (9.00, 22.28), significantly lower than that in the successful weaning group, which was 23.74 (15.49, 30.40). All differences were statistically significant (P < 0.05). When the critical values for RSBI, DE, and DTF were 74 (breaths/min·L), 16.34 mm, and 30.06%, respectively, the sensitivities for predicting successful weaning were 89.29%,80.36% and 76.79%, and the specificities were 65.17%,65.17% and 88.76%, respectively, with the areas under the curve being 0.791, 0.777, and 0.805. The areas under the curve for RSBI combined with DE, RSBI combined with DTF, DE combined with DTF, and all three combined were 0.873, 0.878, 0.868, and 0.917, respectively, with the combination of all three indices having the largest area under the curve.Conclusion Diaphragmatic ultrasound combined with RSBI has high value in the assessment of weaning from mechanical ventilation in neurocritically ill patients.