ObjectiveTo systematically review the relationship between systemic immune inflammatory index (SII) and the prognosis of coronary heart disease. MethodsThe CNKI, VIP, CBM, WanFang Data, PubMed, EMbase, Web of Science, Ovid, Cochrane Library and Scopus databases were electronically searched to collect cohort studies related to the relationship between SII and the prognosis of patients with coronary heart disease from inception to December 10, 2022. Two researchers independently screened the literature, extracted the data and assessed the risk of bias of the included studies. Meta-analysis was then performed by using RevMan 5.3 and Stata 15.0 software. ResultsA total of 7 cohort studies involving 18 413 patients were included. The results of meta-analysis showed that the group of high level SII was higher risk of major adverse cardiovascular events (MACE) (OR=2.2, 95%Cl 1.5 to 3.3, P<0.01), all-cause death (OR=2.0, 95%Cl 1.1 to 3.4, P=0.02), and cardiogenic death (OR=2.4, 95%Cl 1.5 to 3.9, P<0.01) than the group of low level SII. However, no significant difference was found in the risk of re-hospitalization for heart failure. ConclusionThe current evidence shows that high levels of SII can increase the risk of MACE, all-cause death and cardiogenic death in patients with coronary heart disease. Due to the limited quality and quantity of the included studies, more high quality studies are needed to verify the above conclusion.