To find the susceptible genes of ankylosing spondylitis in Chinese population, we select 11 SNPs on gene HLA gene family that has strong linkage of ankylosing spondylitis in 6p21.3. By case-control study in 79 AS patients and 132 healthy subjects, the distribution of TNF-a –850 genotype TT is higher in AS group than that in normal control group (P=0.027); Mutational allele T has a significant statistically difference between AS group and normal control group (P=0.002). By linkage disequilibrium study, there are 5 SNPs present the linkage disequilibrium and the region is 15 kb, including gene LTA, TNF-a, LST1 and NCR3; In the haplotypes of the 5 SNPs , the distribution of haplotype TCTTC has statistical difference between AS group and normal control group (c2=7.406, P=0.0065), the haplotype contains mutational allele T of TNF- a -850. The result hints that there may be susceptible sites of AS in this 15 kb region, which may be TNF-a –850 C→T mutation or other sites that around the TNF-a –850.