Diaphragm dysfunction is common in clinical work, which is a frequently important cause of ventilation weaning failure ignored by clinicians. Assessing diaphragmatic function while weaning helps early detection and prevention of weaning failure, so as to improve the clinical outcome of patients on mechanical ventilation (MV). Reviewing studies of diaphragmatic function evaluation in weaning, we can find that assessing diaphragmatic function during weaning can help guide weaning. Weaning predictors including pressure index, electrophysiological index and morphological index, among which bedside ultrasound as a morphological index is widely used in intensive care unit (ICU), which is simple, non-invasive, and easy to operate. It is also accurate in the assessment of diaphragmatic function and guidance on weaning, which is worthy of promotion and application.