Aim To explore the effect of complete revascularization (CR) on long-term prognosis in elderly patients with acute non-ST-segment elevation myocardial infarction (NSTEMI) complicated with multivessel disease (MVD).Methods According to the management of coronary artery, 603 consecutive elderly patients with acute NSTEMI and MVD were divided into two groups:single culprit revascularization (SR) group (n＝260) and complete revascularization (CR) group (n＝343). The endpoints were set as all-cause death, cardiovascular death, nonfatal reinfarction and unplanned repeat revascularization at one year after percutaneous coronary intervention (PCI) surgery. The effects of CR on long-term prognosis in elderly patients with acute NSTEMI combined with MVD were analyzed by COX regression analysis. Results Compared with SR group, the ratio of previous PCI treatment was lower, ratio of triple-vessel disease and preoperative TIMI 0 or 1 were higher, the number and length of implanted stents were also more and longer, proportion of tiglilol use was higher while proportion of nitrates was lower, in CR group. During the follow-up period, the overall all-cause mortality was 4.8% (SR group vs CR group was 6.2% vs 3.8%, P＝0.179), cardiac mortality was 4.1% (SR group vs CR group was 4.6% vs 3.8%,P＝0.615), rate of nonfatal reinfarction was 2.5% (SR group vs CR group was 1.2% vs 3.5%,P＝0.067), rate of unplanned repeat revascularization was 6.8% (SR group vs CR group was 9.6% vs 4.7%,P＝0.017). The single factor COX regression analysis showed that CR significantly reduced the rate of unplanned repeat revascularization in elderly NSTEMI patients with MVD (HR 0.1,5%CI 0.251-0.882, P＝0.019). After correcting the various clinical factors, the multi-factor COX regression analysis also got the same conclusion (HR 0.8,5%CI 0.229-0.837, P＝0.012). However, no matter single factor analysis or multiple factors analysis, CR had no significant effect on all-cause death, cardiac death and nonfatal reinfarction in elderly NSTEMI patients with MVD. In terms of perioperative complications, there was no significant difference in the incidences of BARC grade 3 or 5 bleeding, contrast-induced nephropathy, stroke and acute stent thrombosis between the two groups. Conclusion CR can significantly reduce the rate of unplanned repeat revascularization in elderly patients with NSTEMI and MVD, and it is also safe during perioperative period.