Purpose: To assess the predictive value of SS II (SYNTAX score II) for long-term outcomes in ST-elevated myoarial infarction (STEMI) patients.  Source: PubMed, EMBASE and Cochrane databases were searched up until September 24, 2021. Two investigators extracted data independently from the relevant articles. A random-effects model was conducted to combine the pooled hazard ratio (HR) or risk ratio (RR) for association between SS II and long term outcomes.  Principal findings: A total of 12 articles (7,195 subjects) were included in the final meta-analyses. Analysis of nine of the articles showed that higher SS II predicted poor long term all-cause mortality among STEMI patients (pooled RRs=4.09,95%CI: 3.49-4.80). A similar association of SS II with poor long term mortality was observed when the crude HRs and adjusted HRs were pooled (crude HRs: pooled HR=1.07, 95%CI: 1.04-1.09; adjusted HRs: pooled HR=1.05, 95%CI:1.04-1.07). The STEMI patients with higher SS II also showed a higher associated with increased risk of long term major adverse cardiac events (pooled HR = 1.05, 95% CI: 1.02-1.07; pooled RR=2.28, 95%CI:2.02-2.57). A consistent association was found for heart failure among STEMI patients.  Conclusion: Higher SS II predicted poor long term all-cause mortality, major adverse cardia events and heart failure among STEMI patients