Background: The relationship between remnant-like particle cholesterol (RLP-C) and cardiovascular disease risk and prognosis has been established, but its effect on the prognosis of ischemic heart failure (IHF) patients undergoing percutaneous coronary intervention (PCI) remains uncertain. Method: In this study, 2036 patients with IHF who underwent PCI were included. Patients were categorized into tertiles based on their RLP-C levels. The primary outcome was major adverse cardiovascular events (MACE). Kaplan-Meier survival analysis was used to assess the incidence of MACE and other outcomes. Multivariate Cox regression models were employed to investigate the correlation between RLP-C and the studied outcomes. The nonlinear relationship between RLP-C and MACE was examined through the restricted cubic spline (RCS). Subgroup analyses were performed and interactions were assessed. Result: The study results showed a clear association between higher RLP-C levels and an increased incidence of MACE in the participants. This association was validated by Kaplan-Meier analyses. The multivariate Cox regression demonstrated RLP-C was an independent risk factor for MACE, whether assessed as a continuous variable[hazard ratio (HR), 95% confidence interval (CI): 1.50, 1.15-1.98, p=0.003] or categorized into tertiles[HR, 95% CI: 2.57, 2.03-3.26, p<0.001, tertile 3 vs tertile 1]. A nonlinear relationship between RLP-C and MACE was observed, indicating that the risk of MACE increased with higher RLP-C levels(Nonlinear p<0.001). This association remained consistent across various subgroups, as no significant interactions were found. Conclusion: There was an independent and positive correlation between RLP-C and MACE in patients with IHF who underwent PCI.