Objective: This study was designed to investigate the effects of early continuous renal replacement therapy in the treatment of cardiac failure combined with acute kidney injury. Methods: Seventy-three cardiac failure patients combined with acute kidney injury admitted to our hospital from November 2017 to February 2019 were enrolled for retrospective analysis. Using random number table, they were divided into the observation group and the control group, of which 36 cases in the control group were given conventional treatment + late continuous renal replacement therapy and 37 cases in the observation group were given conventional treatment + early continuous renal replacement therapy. Physiological indicators, Acute Physiology and Chronic Health Evaluation (APACHE) II scores, haemodynamics, length of ICU stay and mortality rate in both groups were recorded. Results: (1) There was no significant difference in the levels of mean arterial pressure (MAP) and heart rate (HR) between the two groups (P>0.05); (2) APACHE II scores obtained at 1, 2 and 3 weeks after treatment in the observation group were lower than those in the control group (P<0.05); (3) Levels of serum creatinine (Scr), brain natriuretic peptide (BNP) and C-reactive protein (CRP) after treatment in the observation group were lower than those in the control group (P<0.05); (4) The length of ICU stay and hospital stay in the observation group were shorter than those in the control group, so was the mortality rate during hospitalization (P<0.05); and (5) Scores in quality of life questionnaire and kidney disease quality of life-short form (KDQOL-SF) assessed at 1, 2, and 3 months after discharge in the observation group were higher than those in the control group (P<0.05). Conclusion: Early continuous renal replacement therapy in the treatment of cardiac failure combined with acute kidney injury can significantly improve patients' physical conditions and haemodynamics, shorten the length of ICU stay, and lower the occurrence of death, indicating promising application in the future.