Objective To investigate the application of critical ultrasound in evaluating the systolic move⁃ ment（Sm）peak velocity of mitral annula before weaning vein artery extracorporeal membrane oxygenation（VA ⁃ ECMO）. Methods The weaning test was conducted in 40 patients who received VA⁃ECMO treatment in General Hospital of Ningxia Medical University from February 2019 to February 2023. There were 28 cases having success⁃ fully weaning VA⁃ ECMO（group A）and 12 cases failing to wean（group B）. Before weaning test，Sm，left ventric⁃ ular ejection fraction（LVEF），and left ventricular end diastolic diameter（LVEDD）were measured by critical ultrasonography，and the data of two group were analyzed compared . The predicting values of Sm measured by critical ultrasonography for successful weaning were evaluated with ROC curve. Results Before the weaning test，the Sm of group A were higher than those of group B（P < 0.05）. While there was no significant difference in LVEDD between the two groups before weaning test（P > 0.05）. The area under ROC curve（AUC）of Tei index，Sm and LVEF were 0.896，0.479，respectively. The difference of Sm was statistically significant between two groups（all P < 0.05）， and the optimal cut⁃off values were 0.821 and 0.321，respectively. Conclusion Critical ultrasound evaluation of Sm can be used to predict successful weaning of VA⁃ ECMO in ICU patients.