The study was aimed to examine the B cell activating factor promoter polymorphism of the TNF family (BAFF)-871 C/T in patients with immune thrombocytopenic purpura (ITP) and to explore its correlation with ITP and the relationship between the blood platelet count of newly diagnosed patients with ITP and genotypes of BAFF-871 C/T polymorphisms. Alleles specific polymerase chain reaction (ASP-PCR) and agarose gel electrophoresis were used to identify polymorphisms -871 C/T of BAFF promotor in 133 ITP patients and 117 healthy controls, and determine the genotype of subjects. Meantime, the frequency of genotype and alleles were analyzed. The results indicated that out of 133 patients with ITP, 33.1% patients exhibited C/C, 42.1% patients were heterozygous C/T, and 24.8% patients were homozygous T/T. The corresponding frequencies in 117 healthy controls were 55.6% C/C, 33.3% C/T and 11.1% T/T. The allele frequency of T in ITP patients and healthy controls were 45.9% and 27.4% respectively. There was significant difference in the BAFF-871 C/T genotypic frequency between the ITP patients and healthy controls (p < 0.05). The allele frequency of T in ITP patients was higher than that in healthy controls. There was no significant difference in the blood platelet counts between the various genotype (p > 0.05). It is concluded that the polymorphism -871 C/T of BAFF promoter is correlated with the pathogenesis of ITP. However, there is no significant difference in blood platelet counts between the various genotype, so the polymorphism -871 C/T of BAFF promoter can not be referred as the analysis index for evaluating the severity of ITP.