Abstract: Kidney is one of the most frequently injured organs in critical trauma patients. The incidence and mortality of acute kidney injury (AKI) remain high. The ability to predict the occurrence of AKI plays an important role in monitoring its progression. Assessment of renal perfusion is of great clinical significance in early diagnosis of AKI and protection of renal function. Following is a review of the application of ultrasonography in assessment of renal perfusion in critical trauma patients.