ABSTRACT Objective： To evaluate the predictive value of dynamic monitoring changes of lung water combined with diaphragm function in critical patients with mechanical ventilation (MV). Method: Totally 112 critical patients with MV in ICU more than 48 hours were prepared to weaning from MV were enrolled. During the spontaneous breathing trial (SBT), the left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), index of left ventricular diastolic function, and anterior chest wall lung ultrasound edema score (A-LUES 0min) were measured at the 0 min by ultrasound. Diaphragmatic excursion (DE) and A-LUES 15min were measured at the 15min, and △A-LUES (A-LUES 15min - A-LUES 0min) was calculated. ROC curve was used to evaluate the value of each index to predict the weaning outcomes. Results: There were 64 cases weaning successful (successful group) and 48 weaning failure (falure group). LVEF, DE, e’ in falure group were significantly lower than that in successful group, and E/e’, A-LUES 15min, △A-LUES were significantly higher than that in successful group. Choose 51.50%, 6.48cm/s, 10.36, 10.35mm, 1.50 points as the cut-off value of LVEF, e’, E/e’, DE and △A-LUES, the sensitivity were 93.75%, 90.63%, 62.50%, 85.94% and 77.08%, respectively. the specificity were 27.08%, 52.08%, 75.00%, 56.25% and 67.19%, respectively. The AUC were0.613, 0.735, 0.652, 0.786 and 0.793, respectively. Conclusion: dynamic lung ultrasound monitoring combined with diaphragm function and left ventricular dysfunction have better predictive value for the outcomes of weaning.