The invention discloses a reagent for predicting ankylosing spondylitis susceptibility, belonging to the field of medical biotechnology. According to the reagent, the genotype at an SNP site of an AIF1 gene of a subject is determined by extracting genome DNA of a host cell to predict the susceptibility of the subject to ankylosing spondylitis. The reagent disclosed by the invention has the advantages that the correlation between the polymorphic site of the AIF1 gene and the ankylosing spondylitis is expounded for the first time, a method for predicting ankylosing spondylitis susceptibility is provided, and the method can be used for the prevention, auxiliary diagnosis and treatment of the ankylosing spondylitis, and can also be used for the research and development of new medicines.