Objective: To explore and analyze the predictive ability of bedside ultrasound in evaluating cardiac diastolic function, diaphragmatic function and the combination of the two in the weaning results of patients undergoing mechanical ventilation in intensive care unit. Methods: A total of 103 patients with mechanical ventilation who were hospitalized in the intensive care unit of the First Affiliated Hospital of Baotou Medical College from December 2022 to September 2023 were selected. According to the results of spontaneous breathing trial (SBT) before weaning, they were divided into successful weaning group (65 patients) and weaning failure group (38 patients). The diaphragm function index and cardiac diastolic function index of the two groups were observed. The statistical significance of diaphragm function and cardiac diastolic function parameters was statistically analyzed, and the ROC curve was drawn. Results: The successful weaning group exhibited higher LVEF, DE, DTF, e', tricuspid E/A, and TAPSE values compared to the failed weaning group. The successful weaning group exhibited significantly lower values for respiratory rate, E/e', and RVEDA/LVEDA ratio than the failed weaning group (P＜0.05).There was no significant difference in mitral valve E/A value between the successful weaning group and the failed weaning group (P＞0.05). DE, E/e′and TAPSE were the three parameters with the largest AUC in the evaluation of diaphragmatic function and cardiac diastolic function, respectively, and the AUC of the combination of the three was 0.904. Conclusion: Bedside ultrasound assessment of cardiac diastolic function and diaphragmatic function in ICU patients with mechanical ventilation can accurately predict and analyze the weaning results of patients with mechanical ventilation, in order to reduce the occurrence of weaning failure events.