Aim To explore the predictive value of combined detection of red blood cell distribution width (RDW) and N-terminal pro-brain natriuretic peptide (NT-proBNP) for acute kidney injury (AKI) after acute myocardial infarction (AMI). Methods A total of 110 patients with AMI admitted to Beijing Hospital of Integrated Traditional Chinese and Western Medicine from July 2018 to may 2020 were enrolled for retrospective study. Patients were divided into AKI group (n＝29) and non-AKI group (n＝81) according to whether AKI occurred within one week after admission.The levels of RDW and NT-proBNP in AKI group and non-AKI group were detected and compared. The clinical data of the two groups were collected, and the risk factors of AKI after AMI were analyzed by Logistic regression model. The correlation between RDW and NT-proBNP in AMI patients with AKI was analyzed by Pearson linear correlation analysis. The receiver operating characteristic curve (ROC) was drawn and the area under curve (AUC) was determined. The predictive value of RDW, NT-proBNP alone and combined detection for AKI after AMI was analyzed. Results The proportions of three vessel lesion and diuretic use in AKI group were 58.62% and 44.83% respectively, which were significantly higher than 27.16% and 18.52% in non-AKI group (P＜0.01). Uric acid (UA), blood urea nitrogen, serum creatinine, RDW and NT-proBNP levels in AKI group were significantly higher than those in non-AKI group, while estimated glomerular filtration rate (eGFR) was significantly lower than that in non-AKI group (P＜0.01). The results of Logistic regression model showed that the number of lesion, diuretic use and UA, eGFR, RDW, NT-proBNP were the risk factors of AKI in patients with AMI (P＜0.05). RDW was positively correlated with NT-proBNP (r＝0.693, P＜0.05). ROC curve analysis showed that the AUC of RDW, NT-proBNP alone and combined for prediction of AKI after AMI were 0.7,0.788 and 0.871, respectively. Conclusions The increase of RDW and NT-proBNP is closely related to the occurrence of AKI after AMI. The combined detection of RDW and NT-proBNP has high predictive value for the occurrence of AKI in patients with AMI.