Objective To assess the effectiveness and safety of different dual antiplatelet therapies in patients undergoing percutaneous coronary intervention. Methods Such databases as The Cochrane Library, MEDLINE, EMbase, CBM, CNKI and WanFang Data were searched to collect the randomized controlled trials (RCTs) and observational studies on the effectiveness and safety of dual antiplatelet therapies both short-duration (≤6 months) and long-duration (gt;6 months) after percutaneous coronary intervention. The literature was screened according to the inclusive and exclusive criteria by two reviewers independently, the quality was evaluated, the data were extracted, and meta-analyses were performed by using RevMan 5.1 software. Results Eight trials were included, of which 3 were RCTs involving 7 475 patients, and 5 were observational studies involving 12 744 patients. Meta-analyses on RCTs showed that the incidence of death or myocardial infarction in the long-duration treatment group was lower than that of the short-duration treatment group (OR=0.74, 95%CI 0.56 to 0.98, Plt;0.000 1), while meta-analyses on observation studies showed the similar result (OR=0.7, 95%CI 0.45 to 1.08, P=0.11). With the variables of published year and follow-up time, the heterogeneity of cohort studies was discussed through meta-regression (Z=3.61, P=0.000) which indicated that both published year and follow-up time might be the source of heterogeneity due to their contribution. For RCTs, the incidence of severe bleeding events in the short-duration treatment group was lower than that in the long-duration treatment group (OR=1.29, 95%CI 0.99 to 1.69, P=0.06). For observational studies, the incidence of late stent thrombosis in the long-duration treatment group was lower than that in the short-duration treatment group (OR=0.40, 95%CI 0.15 to 1.07, P=0.07). Conclusion The long duration (gt;6months) of dual antiplatelet therapy in patients undergoing percutaneous coronary intervention can reduce the incidence of death or myocardial infarction and decrease the tendency of late stent thrombosis, but cannot obviously increase the incidence rate of severe bleeding events. The current evidence shows no marked superiority in longer duration (gt;12months) of dual antiplatelet therapy.