KIF21B polymorphisms were found associated with susceptibility to multiple sclerosis and ankylosing spondylitis (AS) in populations of white European ancestry. We aimed to replicate the association of polymorphisms around KIF21B and AS in a Chinese Han population. This case-control study included 665 patients with AS and 1,042 healthy controls genotyped for seven single nucleotide polymorphisms (SNPs) of KIF21B--rs12118246, rs4915464, rs502658, rs10494829, rs12089839, rs6687260, and rs957957--by TaqMan genotyping assay; statistical analyses involved the use of PLINK. We also estimated the linkage disequilibrium and haplotypes of these SNPs. Two SNPs--rs502658 (allelic p = 0.0002, odds ratio [OR] 0.60, 95 % confidence interval [95 % CI] 0.47-0.76) and rs10494829 (allelic p = 0.003, OR 1.30, 95 % CI 1.12-1.52)--were significantly associated with AS in the Chinese Han population. In addition, a linear regression test showed that they have independent contribution to disease susceptibility. For both SNPs, haplotype AT was strongly associated with AS and increased the risk of the disease (p = 0.045, OR 1.183, 95 % CI 1.004-1.395), and the genotype GC reduced the risk (p = 0.011, OR 0.715, 95 % CI 0.55-0.928). This work identified a significant association of two SNPs in KIF21B and AS in the Chinese Han population. KIF21B may play an important role in the pathogenesis of AS in the Chinese population and might be a new therapeutic target for AS.