There are significant differences in the incidence and risk factors of tumor patients, and there is no relevant statistical data. Therefore, this study aims to clarify the incidence and risk factors of acute kidney injury (AKI) in malignant tumor patients and compare critically ill patients with non-critically ill patients.Relevant literature on the occurrence of AKI in malignant tumors was retrieved from databases. Two authors independently screened and evaluated the eligibility and quality of the literature and extracted the data. The Stata 12.0 software was used for meta-analysis.A total of 3922 articles were initially retrieved, and 24 articles were finally included, 8 of which were about critically ill malignant tumor patients, and 16 were about malignant tumor patients. Among the 4107 patients included in the 8 studies on critically ill malignant tumors, 1932 developed AKI, with an incidence rate of 52% (95%CI 34-70%, I2 = 99%). The risk factors for AKI in critically ill malignant tumor patients were sepsis and hypovolemia, which were different from those in non-critically ill patients. Among the 292,874 patients included in the 16 studies on malignant tumors, 51,211 developed AKI, and the combined incidence rate was 24% (95%CI 17-30%, I2 = 100%). The risk factors for AKI in critical malignant tumor patients were sepsis and hypovolemia.This meta-analysis shows that the incidence of AKI in critically ill malignant tumor patients is consistent with that in other critically ill patients, and independent risk factors are sepsis and hypovolemia. The incidence of AKI in malignant tumor patients is higher than that in other patients, and tumor is a risk factor for AKI. This study has been registered in INPLASY (INPLASY202320079),Registered February 18,2023.© 2023. The Author(s).