Abstract： Objective:To explore the application value of ultrasound diaphragmatic function assessment in weaning from invasive mechanical ventilation in patients with respiratory failure.Method:Fifty-three patients with acute respiratory failure who underwent mechanical ventilation and weaning in People’s Hospital Affiliated to Ningbo University from January 2020 to February 2022 were selected for research. After weaning conditions, T-tube was used for spontaneous breathing test (SBT). At SBT-30 min, beside ultrasound was used to collect the right diaphragm movement (DE) and diaphragm thickness, and the shallow rapid breathing index (RSBI), diaphragm shallow rapid breathing index (D-RSBI) and diaphragm thickness change rate (DTF) were calculated. According to the outcome of weaning, the patients were divided into the successfully weaned group and unsuccessfully weaned group. All patients’ clinical data were collected, and the relationship between ultrasound parameters and clinical indexes was compared between the two groups The efficiency of each index for predicting the success rate of weaning was analyzed with the receiver operating characteristic (ROC) curve.Results:Fifty-three patients were enrolled in this study, including 36 patients in the successfully weaned group and 17 patients in the unsuccessfully weaned group. DE and DTF in the successfully weaned group were higher than those in the unsuccessfully weaned group (all P<0.05), RSBI and D-RSBI in the successfully weaned group were significantly lower than those in the unsuccessfully weaned group (all P<0.05). ROC curve analysis showed that when the cut-off value of DE, DTF, RSBI and D-RSBI were >1.21 cm, >27.5%, <48.68 times/(min·L) and <1.31 times/(min·mm), the sensitivity of predicting the success of weaning was 69.0%, 97.2%, 83.0% and 83.0% respectively, and the specificity was 59.0%, 47.1%, 94.1% and 94.3%, respectively. Conclusions:The evaluation of ultrasound diaphragmatic function can effectively guide the clinical mechanical ventilation patients to withdraw the machine, and improve the accuracy of predicting the success rate of weaning. Therefore, t ultrasound diaphragmatic function assessment has a high application value in guiding the mechanical evacuation of patients with mechanical ventilation, and can be widely applied in clinical practice.