Background Reperfusion therapy as early as possible in patients with acute ST-segment elevation myocardial infarction (STEMI) can reduce myocardial necrosis,and thus decrease mortality and improve prognosis.Therefore,shortening door-to-ballon (D2B) time is critically important.However,whether using a single guiding catheter (JL3.5) for transradial coronary angiography and intervention can reduce D2B time and improve prognosis is unknown yet.Methods From December 2012 to December 2015,185 patients with STEMI receiving emergent coronary angiography (CAG) and primary percutaneous coronary intervention (PCI) were retrospectively enrolled and divided into two groups:treatment group (use a single JL 3.5 guiding catheter,n =87) and control group (routine catheter,n =98).Clinical data,complications rates,procedure time and outcomes in 1 year between the 2 groups were analyzed.Results There were significant reduction in D2B time,surgery time and contrast consumption in treatment group.Incidence of in-hospital death (2.3％ vs.10.2％,P =0.029) and MACEs (12.6％ vs.27.6％,P =0.029) were also lower in treatment group.All patients had completed the one-year follow up and 21 patients died.The difference in one-year mortality were statistically significant between two groups (4.6％ vs.17.3％,P =0.006).Multiple logistic analysis showed that the using of single JL3.5 was independently associated with decreased risk of one-year mortality (OR =0.11,95％CI:0.02-0.47,P =0.003).Conclusions A single guiding catheter (JL 3.5) in patients with STEMI is feasible and safe.It can reduce D2B time,procedure time,contrast consumption and risk of one-year mortality.