Postoperative acute kidney injury (AKI) is a common postoperative complication. The current guideline of Kidney Disease: Improving Global Outcomes (KDIGO) sets serum creatinine (SCr) and urine volume as the diagnostic criteria, which have low timeliness and accuracy. By describing several functional biomarkers of renal injury, biomarkers of renal tubular injury, and other biomarkers identified in current studies, this review aims to obtain early indicators of AKI injury in clinical practice, know subclinical AKI status, predict postoperative AKI stage, and distinguish persistent AKI. In addition, it can accurately judge long‑term important renal adverse events and related mortality.