Objective: As incidences of kidney disease increase, patients with this disease are prone to ischemia/reperfusion acute kidney injury after surgery; this not only affects their quality of life after surgery, but also increases the burden on their kidneys. Cystatin C (Cys C) plays an important role in the treatment of ischemia/reperfusion acute kidney injury (AKI) disease. Therefore, it is necessary to study the role of Cys C in the progression of AKI disease. The purposes of this article are to analyse the changes and significance of Cys C in the urine of rats with ischemia/reperfusion AKI and to establish a rat model of ischemia/reperfusion AKI. Methods: According to their perfusion time, the rats were divided into four groups: 0, 10, 20, and 30 min. Next, the urine Cys C and renal tubular necrosis score were measured. Results: The results of the study show that the baseline urine Cys C levels of rats in each group were in the vicinity of 0.29, 0.79, 1.22, and 1.32 mu g/L, respectively. After 24 hours of reperfusion, the level of urinary Cys C in the 0-min renal ischemia group did not change significantly, while the level of urinary Cys C increased significantly in the 10-, 20-, and 30-min renal ischemia groups. Conclusion: It is evident that changes of Cys C in the urine of rats with ischemia/reperfusion acute kidney injury is of great significance for the detection of AKI.