Objective To investigate the value of severe ultrasound monitoring of excursion of diaphragm in prediction of weaning ability in patients with mechanical ventilation in intensive care unit (ICU).Methods The clinical data of 100 patients with respiratory failure who admitted to our hospital from May 2018 to December 2019 were retrospectively analyzed, and they were divided into successful withdrawal group (77 cases) and failed withdrawal group (23 cases)according to withdrawal situation.The excursion of diaphragm of patients was measured by ultrasound instruments, and the ROC curve was used to evaluate the predictive value of excursion of diaphragm in weaning ability of patients with mechanical ventilation in ICU.Results The 0.1 s airway occlusion pressure (P0.1) and rapid-shallow-breathing index(RSBI) in failed withdrawal group group were higher than those in successful withdrawal group, and the left excursion of diaphragm, right excursion of diaphragm and mean excursion of diaphragm in failed withdrawal group group were lower than those in successful withdrawal group (P<0.05);After analysis of the ROC curve, the area under the ROC curve (AUC) obtained by P0.1 was 0.831, when the optimal cutoff value was 2.50 cmH2O, the sensitivity was 0.739 and the specificity was 0.299.The AUC obtained by RSBI was 0.839, when the optimal cutoff value was 45.40, the sensitivity was 0.783 and the specificity was 0.208.The AUC obtained by left excursion of diaphragm was 0.904, when the optimal cutoff value was 0.77 cm, the sensitivity was 0.870 and the specificity was 0.234.The AUC obtained by right excursion of diaphragm was 0.901, when the optimal cutoff value was 1.12 cm, the sensitivity was 0.826 and the specificity was 0.208.The AUC obtained by mean excursion of diaphragm was 0.909,when the optimal cutoff value was 1.00 cm,the sensitivity was 0.913 and the specificity was 0.494.Conclusion Severe ultrasound monitoring of excursion of diaphragm has higher application value in prediction of weaning ability in patients with mechanical ventilation in ICU.