AIM: To study the effect of timing of percutaneous coronary intervention (PCI) to prognosis of Non-ST segment elevation myocardial infarction (NSTEMI) patients. METHODS: 295 Patients were derived from our hospital who were diagnosed as NSTEMI and accepted PCI therapy in 24 hours from admission during March 2017 to May 2020. According to results of coronary angiography, patients with NSTEMI were divided into culprit artery occlusion (CO, n = 117) and non-culprit artery occlusion (N-CO, n = 178) two groups and then according to timing of PCI into three categories: <6 h, 6–12 h and 12–24 h from admission. We defined major adverse cardiovascular events (MACE) in 1 year follow. RESULTS: In this study, with earlier time to PCI, the incidence of MACE was lower in NSTEMI patients with CO. The incidence of MACE was higher in the CO group than in the N-CO group (25.8% vs. 36.8%, p = 0.046). The incidence of MACE was 11.8% in T1 (<6 h) group (n = 50), less than 29.4% in T2 (6–12 h) group (n = 30) and 43.4% in T3 (12–24 h) group (n = 215), with a statistically significant difference (p = 0.044). However, this phenomenon does not occur in N-CO group. As the duration of PCI increased, patient survival decreased progressively over the course of follow-up in NSTEMI with CO (p = 0.048). CONCLUSIONS: Our study found that early PCI improves the prognosis of NSTEMI patients with culprit artery occlusion.