Aim To investigate the clinical factors which influence platelet aggregation function in patients after percutaneous coronary intervention(PCI). Methods A retrospective study was conducted on 266 patients with coronary heart disease which underwent PCI. All patients were treated with clopidogrel and aspirin dual anti-platelet therapy and standard medication. Patients were divided into 0%~29%, 30%~49%, 50%~69%, 70%~100% groups according to the adenosine diphosphate(ADP)-induced platelet aggregation rate(PAR). The CYP2C19 genotypes, general clinical information, lab indexes and coronary artery lesions after PCI were compared among the four groups. Risk factors of elevated PAR were explored by logistic regression analysis. Results There were significant differences in gender ratio, age, brain natriuretic peptide(BNP), CYP2C19 genotype among four groups of PAR(P<0.05). Logistic regression analysis revealed that female(OR=2.713, P=0.027), higher BNP(OR=1.002, P=0.007), slow metabolism genotype(OR=5.159, P<0.001) were risk factors for PAR≥50%; and female(OR=5.716, P=0.008), slow metabolism genotype(OR=3.149, P=0.049) was independent risk factor for PAR ≥70%. Conclusion Majority of patients with PAR<50% were fast metabolism genotype, and patients with slow metabolism genotype usually had PAR more than 50%; CYP2C19 polymorphism had strong impact to PAR. In addition, female and higher BNP might be risk factors of elevated PAR in patients with coronary heart disease after PCI.