Ankylosing spondylitis (AS) is a largely genetically determined autoimmune disease. JMY has recently been found to be associated with susceptibility to AS in patients of western European descent. We aimed to examine the influence of JMY polymorphisms on the severity of AS in the Chinese ethnic majority Han population. Blood samples were drawn from 396 Chinese Han AS patients whose duration of disease was about 9-12 years. Four tag single-nucleotide polymorphisms (tagSNPs) in JMY were selected and genotyped. Frequencies of different genotypes and clinical indexes about the severity of AS were analyzed. The rs2607142, rs16876619, and rs4704556 SNPs are related to BASFI. The rs2607142, rs4704556, and rs16876657 SNPs are related to BADAI. The rs4704556 and rs16876657 SNPs are related to mSASSS. JMY is related to the severity of AS in Chinese Han patients.