Background: The timely weaning of mechanical ventilation can shorten intensive care unit (ICU) stay times and reduce the complications related to mechanical ventilation. This study sought to investigate the predictive role of a weaning index (WI) on mechanical ventilation evacuation by measuring minute ventilation volume (MVV) across different ventilation modes.Methods: Patients suffering from respiratory failure for a variety of reasons were included in the study if they received mechanical ventilation for more than 48 hours in the ICU. The patients were randomly allocated to either the assist/control (A/C) group or the pressure support ventilation (PSV) group according to the ventilator mode. The factors associated with weaning success and failure were analyzed.Results: A total of 40 patients participated in this study. Of these, 25 weaning cases were successful and 15 were failures. There were 19 cases in the A/C group, yielding a success rate of 63%, and 21 cases in the PSV group, yielding a success rate of 62%. There were no significant differences between the two groups in terms of age, gender, ideal weight, Acute Physiology and Chronic Health Evaluation (APACHE) II score, ICU stay time and hospitalization time. There were significant differences in the mechanical ventilation duration between the two groups (P<0.05). When the WI was less than 50.44, the sensitivity and specificity of predicting weaning success were 72% and 98%. The area under the receiver operating characteristic (ROC) curve was 0.928±0.03. When the WI of the A/C group was less than 61.45, the sensitivity and specificity of predicting weaning success were 98% and 72%, respectively. The area under the ROC curve was 0.917±0.068.When the WI of the PSV group was less than 51.45, the sensitivity and specificity of predicting weaning success were 74.6% and 100%, respectively. The area under the ROC curve was 0.933±0.046.Conclusions: Compared with RSBI, WI shows a better value in predicting weaning, especially for mechanically ventilated patients in PSV mode, WI has greater value in predicting weaning.